document_title: Gun laws in Virginia

question_text: do you need a permit to buy a gun in va

question_tokens: do you need a permit to buy a gun in va

text: Gun laws in Virginia

text: Summary table[edit]

text:
Subject/Law
Long Guns
Handguns
Relevant Statutes
Notes

Permit to purchase required?
No
No

Firearm registration?
No
No
§ 18.2-295
Fully-automatic firearms (machine guns) are required to be registered with the state police.

Owner license required?
No
No

Proof of age and citizenship required for the purchase of "assault weapons".

Concealed carry permits required?
No
Yes
§ 18.2-308
Virginia is a "shall issue" state for concealed carry. Permits are issued to non-residents and training is permitted online or in person.

Open carry permitted?
Yes
Yes
§ 15.2-915.2
§ 18.2-287.4
§ 18.2-282

Open carry is generally allowed without a permit for people 18 years of age and older. The following cities and counties have exceptions that disallow the open carry of "assault weapons" (any firearm that is equipped with a magazine that will hold more than 20 rounds of ammunition or is designed by the manufacturer to accommodate a silencer or equipped with a folding stock) or shotguns equipped with a magazine that holds more than 7 rounds: the Cities of Alexandria, Chesapeake, Fairfax, Falls Church, Newport News, Norfolk, Richmond, and Virginia Beach and in the Counties of Arlington, Fairfax, Henrico, Loudoun, and Prince William. These restrictions do not apply to valid concealed carry permit holders. Stated differently, you may open carry an assault weapon/shotgun with more than 7 rounds with a permit in the aforementioned locations, but do not need a permit to do so in any other locality in Virginia.
For open carry in a vehicle, the firearm must be "properly secured in a container or compartment within the vehicle" (ie glove box, center console, trunk, etc). The container/compartment does not have to be locked, the firearm may be within the reach of the driver or a passenger, and the firearm may be loaded. This does not preempt an employer from prohibiting firearms "at a place of employment if there is a company policy or signage prohibiting firearms on the premises."[3] Furthermore, a "county or city may by ordinance make it unlawful for any person to transport, possess or carry a loaded shotgun or loaded rifle in any vehicle on any public street, road, or highway within such locality." However, this does not "apply to duly authorized law-enforcement officers or military personnel in the performance of their lawful duties, nor to any person who reasonably believes that a loaded rifle or shotgun is necessary for his personal safety in the course of his employment or business."
In addition, a firearm may be considered "open carry" in a vehicle if the firearm is openly visible, though this is not as well established as the "secured in a container/compartment" rule.

State preemption of local restrictions?
Yes
Yes
§ 15.2-915
Virginia has state preemption for most but not all firearm laws.

Rifle weapon law?
Yes
Yes
§ 18.2-308.2:2
§ 18.2-308.2:01 § 18.2-308.7

Proof of age (18+ for long arms, 21+ for pistols) and proof of citizenship (or permanent residence license) are required for the purchase of "assault weapons". "Assault weapons" are defined as a semi-automatic, centerfire, firearm equipped with a folding stock, or equipped at the time with a magazine capable of holding more than 20 rounds, or capable of accommodating a silencer/suppressor.

Magazine restriction?
No
No
§ 18.2-287.4
§ 18.2-282.

Magazines capable of holding more than 20 rounds are legal but, they make the firearm an "assault weapon", subject to law accordingly.

NFA weapons restricted?
No
No
§ 18.2-308.8
§ 18.2-308.5
§ 18.2-295
Fully-automatic firearms (machine guns) must be registered with the state police. Plastic firearms and some destructive devices (such as the striker 12 shotgun) are prohibited outside law enforcement. SBS, SBR, AOWs, and suppressors are legal with NFA paperwork.

Background checks required for private sales?
No
No

tag: table

text:
Gun laws in Virginia

Constitution

Constitution sections
Article I, §13.

[show]
Synopsis

"[...] the right of the people to keep and bear arms shall not be infringed; [...]"

Preemption and local regulation

Preemption sections
§ 15.2-915.,
§ 15.2–915.1.,
§ 15.2–915.2.,
§ 15.2–915.4.,
§ 15.2-914.

[show]
Synopsis

Localities may regulate the transportation of a loaded rifle or shotgun, regulate the use of pneumatic guns, and the possession and storage of firearms by persons who provide child-care services.

Registration

Ownership registration sections
§ 18.2–295.

[show]
Synopsis

Machine guns must be registered with the Virginia State Police.[4]

[show]
Purchase registration

No purchase registration

[show]
Lost/stolen registration

No lost/stolen registration

Restricted or prohibited items

Restricted firearms sections
§ 18.2–308.8.,
§ 18.2–308.5.

[show]
Synopsis

Armsel Striker, also known as the Striker 12, and similar shotguns are prohibited. Plastic firearms are prohibited.

[show]
Restricted ammunition

No restricted ammunition

[show]
Restricted accessories

No restricted accessories

Restricted or prohibited places

Restricted places sections
§ 18.2–283.,
AG Opinion 11-043,
§ 18.2–283.1.,
§ 18.2–287.01.,
§ 18.2–287.4.,
§ 18.2–308.1.,
4VAC15-40-60.,
4VAC10-30-170.,
8VAC35-60-20.
GA JRC Rule,
§ 18.2–308.

[show]
Synopsis

Places of religious worship, without good and sufficient reason. The Attorney General has opined that personal protection constitutes a good and sufficient reason.
Courthouses.
Air carrier airport terminals.
Certain high-capacity firearms in public places in certain counties and cities; except certain persons.
Public, private or religious elementary, middle or high schools and associated buildings, grounds, buses, and events; except certain persons.
On George Mason University property in academic buildings, administrative office buildings, student residence buildings, dining facilities, or while attending sporting, entertainment or educational events; except police officers.
Anywhere on a Virginia Commonwealth University campus, without the written authorization of the president of the university; except persons whose duties lawfully require the possession of firearms.
The Capitol and the General Assembly building; except for members of the General Assembly, persons with concealed handgun permits, and law enforcement personnel.
Private property where prohibited by the owner.

Restricted or prohibited persons

Underage persons sections
§ 18.2–56.2.,
§ 18.2–308.7.

[show]
Synopsis

Persons under the age of 12, except while supervised.
Persons over the age of 12, but under the age of 18, except while supervised; or unsupervised with parental and property owner permission.

Alien persons sections
§ 18.2–308.2:01.

[show]
Synopsis

Persons who are not lawfully present in the United States may not possess, transport or carry any firearm.
Persons who are not citizens or lawful permanent residents may not possess an "assault firearm."

Restricted persons sections
§ 18.2–308.1:1.,
§ 18.2–308.1:2.,
§ 18.2–308.1:3.,
§ 18.2–308.1:4.

[show]
Synopsis

Persons acquitted by reason of insanity.
Persons adjudicated legally incompetent, mentally incapacitated.
Persons involuntarily admitted to a facility or ordered to mandatory outpatient treatment.
Persons subject to protective orders.

Convicted persons sections
§ 18.2–290.,
§ 18.2–308.1:5.,
§ 18.2–308.2.

[show]
Synopsis

Persons convicted of a crime of violence in any court of record may not possess a machine gun.
Persons convicted of certain drug offenses; for a period of five years.
Persons who have been convicted of a felony, kidnapping, robbery by the threat or presentation of firearms, or rape.

Manufacturing

Manufacturing regulations sections
§ 18.2–294.,
§ 18.2–304.,
§ 18.2–308.5.

[show]
Synopsis

Manufacturers must keep a record of all machine guns, sawed-off rifles and sawed-off shotguns that they manufacture.
Manufacturers are subject to police inspection of their stock of machine guns, sawed-off rifles, and sawed-off shotguns.
It is unlawful to manufacture firearms containing less than 3.7 ounces of electromagnetically detectable metal in the barrel, slide, cylinder, frame or receiver.

Sale, purchase, and transfer

Dealer regulations sections
§ 18.2–294.,
§ 18.2–304.,
§ 18.2–308.2:1.,
§ 18.2–308.2:3.
§ 18.2–308.2:2.,

[show]
Synopsis

Dealers are subject to police inspection of their stock of machine guns, sawed-off rifles, and sawed-off shotguns.
Dealers may not sell or otherwise furnish firearms to any person he knows is prohibited from possessing or transporting a firearm.
Criminal background checks of employees of gun dealers are required before they may transfer firearms.
Criminal history record information check required for the transfer of certain firearms.
Non-residents may purchase rifle and shotguns only

Private sale regulations sections
§ 18.2–308.2:1.,
§ 18.2–308.2:2.

[show]
Synopsis

Private sellers may not sell or otherwise furnish firearms to any person he knows is prohibited from possessing or transporting a firearm.
Private sellers may sell long guns and handguns.

Transportation and carry

Transportation restrictions sections
§ 15.2–915.2.,
§ 18.2–308.

[show]
Synopsis

Localities may regulate the transportation of a loaded rifle or shotgun.
Persons lawfully possessing a handgun may transport such handgun loaded and in a secure compartment in a vehicle or vessel.

Open carry restrictions sections
§ 18.2–308.

[show]
Synopsis

There is no law against a law-abiding citizen openly carrying a firearm, therefore it is legal and no permit or license is required.[5]
"Open carry" is the carrying of a firearm that is not concealed. Virginia defines concealed as "hidden from common observation" and "a weapon shall be deemed to be hidden from common observation when it is observable but is of such deceptive appearance as to disguise the weapon's true nature."

Concealed carry restrictions sections
§ 18.2–308,
§ 18.2–308.012

[show]
Synopsis

Only persons who hold certain positions, comply with certain rules or restrictions, and/or who have a Concealed Handgun Permit (CHP) may carry concealed handguns.
Virginia issues a CHP to residents and non-residents.
CHP applicants must provide proof of demonstrated competence with a handgun.
Some persons are deemed disqualified from obtaining a CHP, even though they may lawfully possess and carry a firearm.
Virginia maintains concealed handgun permit reciprocity with other States and recognizes some licenses from other States without a formal reciprocity agreement. The list of such states is maintained by the Virginia State Police.[6]
Consuming an alcoholic beverage in ABC on-premises licensed restaurants and clubs, while carrying a concealed handgun, is prohibited. Openly carrying and consuming an alcoholic beverage is permitted. No person may carry a concealed handgun in a public place while under the influence of alcohol or illegal drugs.
§ 18.2–308, which regulates concealed weapons, shall not apply to any person while in his own place of abode or the curtilage thereof.
Except as provided in subsection J1, being "under the influence", § 18.2–308 shall not apply to:

Any person while in his own place of business;
Any person who may lawfully possess a firearm and is carrying a handgun while in a personal, private motor vehicle or vessel and such handgun is secured in a container or compartment in the vehicle or vessel;
Certain current and retired law-enforcement officers and certain State employees.

text: Overview[edit]

text: The Constitution of Virginia protects the right of the people to keep and bear arms from government infringement.[7] The Commonwealth of Virginia preempts local regulation of several aspects of firearms, though some local regulation is explicitly permitted. Virginia passed the Uniform Machine Gun Act, which was drafted by the National Conference of Commissioners on Uniform State Laws.[8][9] The only firearms in Virginia that are prohibited are the Armsel Striker, also known as the Striker 12, similar shotguns, and any "plastic firearms." Firearms must contain at least 3.7 ounces of electromagnetically detectable metal in the barrel, slide, cylinder, frame or receiver, and when subjected to x-ray machines, generate an image that accurately depicts their shape.[10] For example, Glock pistols which have polymer frames and metal slides and barrels are legal. There are no magazine capacity limitations, except that a concealed handgun permit (CHP) is required in order to carry magazines with more than 20 rounds in some urban, public areas.[1][2]

text: Prohibited places include courthouses, air carrier terminals, schools, Capitol and General Assembly buildings (open carrying only, members of the General Assembly and those with a valid CHP are permitted in the Capitol General Assembly buildings), and churches, though some exceptions apply, including a 2011 Attorney General opinion that personal protection constitutes good and sufficient reason to carry at a church.[11] George Mason University, Virginia Commonwealth University, and Virginia Polytechnic University (Virginia Tech) currently possess rules that prohibit firearms on school property.

text: A 2006 opinion issued by State Attorney General Robert F. McDonnell stated “...the governing boards of Virginia’s public colleges and universities may not impose a general prohibition on the carrying of concealed weapons by permitted individuals... Pursuant to specific grants of statutory authority, however, it is my opinion that colleges and universities may regulate the conduct of students and employees to prohibit them from carrying concealed weapons on campus.”[12]

text: In 2011, the Virginia Supreme Court found that the language used by George Mason University (GMU) to “...not impose a total ban of weapons on campus. Rather, the regulation is tailored, restricting weapons only in those places where people congregate and are most vulnerable – inside campus buildings and at campus events. Individuals may still carry or possess weapons on the open grounds of GMU, and in other places on campus not enumerated in the regulation.”[12]

text: There are age restrictions on the possession of firearms and some people are prohibited from possessing firearms due to certain criminal convictions. Licensed dealers must have the Virginia State Police conduct a background check prior to completing the sale of certain firearms. Persons who are not in the business of selling firearms, but make occasional, private sales, are not required to perform a background check before selling their firearms. Before July 1, 2012, a person could not purchase more than one handgun per 30-day period, though some exceptions applied; most significantly, holders of valid Concealed Handgun Permits (CHP) from Virginia were exempt from this restriction.[1][2] The bill that repealed the "one-handgun-a-month law" was signed into law by Governor Bob McDonnell on February 28 of that year.[13]

text: Open carry of a handgun without a permit is legal in Virginia at age 18, withstanding other applicable laws. Concealed carry of a handgun is allowed for persons who hold a valid CHP (concealed handgun permit), comply with certain restrictions, or who hold certain positions. Virginia shall issue a CHP to applicants 21 years of age or older, provided that they meet certain safety training requirements and do not have any disqualifying criminal convictions. Consuming an alcoholic beverage in ABC on-premises licensed restaurants and clubs, while carrying a concealed handgun, is prohibited; nor may any person carry a concealed handgun in a public place while under the influence of alcohol or illegal drugs. Any person permitted to carry a concealed firearm may not carry one in such manner in a public place while intoxicated. Possession of a firearm can compound the penalty for various other offenses, including illegal drug possession. Open carry while intoxicated is not addressed in the law and can presumed to be legal unless otherwise specified.[14][1][2][15]

text: There are some restrictions on the use of weapons. Brandishing a firearm is punishable by up to a year in jail.[16]


document_title: Lark Rise to Candleford (TV series)

question_text: where does lark rise to candleford take place

root

text: Lark Rise to Candleford (TV series)

text: Premise[edit]

text: The series is set in the small Oxfordshire hamlet of Lark Rise and the wealthier neighbouring market town of Candleford towards the end of the 19th century. The series chronicles the daily lives of farm workers, craftsmen, and gentry, observing the characters in loving, boisterous, and competing communities of families, rivals, friends, and neighbours.

tag: p

text: The story is seen through the eyes of a teenage girl, Laura Timmins (Olivia Hallinan), as she leaves Lark Rise to start a new life under the wing of her mother's cousin, the independent and effervescent Dorcas Lane (Julia Sawalha), who is Post Mistress at the local Post Office in Candleford. Through these two characters, viewers experience the force of friendship as Laura and Dorcas see each other through the best and worst of times.

text: Cast[edit]

text: Main cast[edit]

text:
Character
Portrayed by
Seasons

Series 1
Series 2
Series 3
Series 4

Dorcas Lane
Julia Sawalha
Main

Laura Timmins
Olivia Hallinan
Main

Emma Timmins
Claudie Blakley
Main

Robert Timmins
Brendan Coyle
Main
N/A

Victoria May 'Queenie' Warrener Turrill
Linda Bassett
Main

Thomas 'Twister' Turrill
Karl Johnson
Main

Thomas Brown
Mark Heap
Main

Margaret Ellison Brown
Sandy McDade
Recurring
Main

Caroline Arless
Dawn French
Main
N/A
Main

Alf Arless
John Dagleish
Main

Winifred 'Minnie' Mude
Ruby Bentall
N/A
Main

Zillah
Liz Smith
Main
N/A

Prudence 'Pearl' Pratt
Matilda Ziegler
Main

Ruth 'Ruby' Pratt
Victoria Hamilton
Main

Sir Timothy Midwinter
Ben Miles
Main
N/A

Lady Adelaide Midwinter
Olivia Grant
Main
N/A
Guest
N/A

Phillip White
Oliver Jackson-Cohen
Main
N/A

Mr. Paxton
Gerard Horan
Main
N/A

Matthew Welby
Stephen Marcus
Main
N/A

James Dowland
Jason Merrells
N/A
Main
N/A

Nan Carter
Rebecca Night
N/A
Main
N/A

Daniel Parish
Ben Aldridge
N/A
Main

Gabriel Cochrane
Richard Harrington
N/A
Main

Narrator (Adult Laura Timmins)
Sarah Lancashire
Recurring

Edmund Timmins
Thomas Rhys Jones
Recurring

Frank Timmins
Fergus Drysdale
Recurring

Ethel Timmins
Martha Murdoch
Recurring

Sally Arless
Sophie Miles
Recurring

Lizzie Arless
Hope Yeomans
Recurring

Archie Arless
Harry Miles
Recurring
N/A

Sydney Dowland
Edward Darnell-Hayes (Oscar Lloyd in 1 episode in Series 2)
N/A
Guest
Recurring

Fisher Bloom
Matthew McNulty
N/A
Recurring
N/A

text: Casting notes[edit]

text: From Series 1 to 3, the cast were credited alphabetically. Series 4 cast members were billed in the order of prominence within each episode.

text: Dawn French is credited as a main cast member in every episode in which she appears; in series 2 and series 4 she appears in one episode.

text: Although they appear in almost every episode, the actors playing the Timmins (Edmund, Frank and Ethel) and Arless (Lizzie, Archie and Sally) children as well as Sydney Dowland are not credited as main cast members.

text: Guest stars[edit]

text:
Lorraine Ashbourne as Lil Spicer (Series 2, 1 episode)
Samantha Bond as Celestia Brice-Coulson (Series 2, 1 episode)
Rosie Cavaliero as Mrs Mullins (Series 3, 1 episode)
Camille Coduri as Patty (Series 1, 1 episode)
Tom Conti as Mr. Reppington (Series 3, 1 episode)
Ben Daniels as Mr. Rushton (Series 1, 1 episode)
Phil Davis as Arthur Ashlow (Series 1, 1 episode)
Oliver Dimsdale as George Ellison (Series 2, 4 episode)
Michelle Fairley as Elizabeth Patterson (Series 2, 10 episode)
Burn Gorman as Benedict Marley (Series 4, 1 episode)
Nigel Harman as Samuel Braby (Series 1, 1 episode)
Matthew McNulty as Fisher Bloom (Series 2, 3 episodes; Series 3, 2 episodes)
Stephen Campbell Moore as James Delafield (Series 1, 1 episode)
Hattie Morahan as Miss Enid (Series 3, 1 episode)
Ronald Pickup as Old Peg Leg (Series 3, 1 episode)
Robert Pugh as Walter Arless (Series 2, 1 episode; mentioned throughout Series 1)
Paul Ritter as Mr Steerforth (Series 4, 1 episode)
Claire Skinner as Mrs Macey (Series 1, 2 episodes)
Sheridan Smith as Cinderella Doe (Series 2, 1 episode)
Maggie Steed as Mrs Herring (Series 2, 1 episode)
Peter Vaughan as Reverend Ellison (Series 1, 2 episodes)
Danny Webb as Mr Macey (Series 1, 1 episode)

tag: ul

text: Filming[edit]

text: Interior scenes were shot in a warehouse on Beeches Industrial Estate, in Yate, South Gloucestershire. The villages of Lark Rise and Candleford were both created from scratch on farms in Box and Neston Park, near Corsham in Wiltshire.[5] According to the BBC planning application, Hatt Farm in Box was used because of its proximity to existing cornfields and farm buildings, and Park Farm in Neston Park was chosen for its unspoilt character and attractive traditional buildings.[6]

text: The outdoor filming at these locations for the first series took 25 days, spread over a 5-month period.[6] The country scenes, including all the comings and goings of the lord of the manor, were shot at Chavenage House north of Tetbury, Gloucestershire.[7][8]

text: Episodes[edit]

text: Series 1 (2008)[edit]

text:
#
Episode
Writer
Director
Original air date
Viewing figure[9]

1
"Episode 1"
Bill Gallagher
Charles Palmer
13 January 2008 (2008-01-13)
7.27 million

Young country girl Laura Timmins leaves her friends and family in the hamlet of Lark Rise to start her first job at the post office in the nearby town of Candleford. Postmistress Dorcas Lane gives Laura a warm welcome, but other residents of Candleford aren't so generous. When Lark Rise residents challenge the post office's 'eight-mile rule' that forces them to pay for delivery of telegrams, Laura finds herself torn between communities. By the quiet intervention of Dorcas, a way is found for the hamlet to be included within the limit. The episode ends with the inhabitants celebrating their victory.

2
"Episode 2"
Bill Gallagher
Charles Palmer
20 January 2008 (2008-01-20)
7.01 million

Postwoman Mrs Macey receives news that her husband Dan has escaped from prison. Before long the whole town is abuzz with gossip, and Mrs Macey fears that the damage to her reputation will force her to leave Candleford. Meanwhile, her son Freddy has been secretly meeting a mysterious stranger in the woods. The stranger turns out to be Dan, but he is persuaded to turn himself in to the local squire and magistrate.

3
"Episode 3"
Bill Gallagher
Charles Palmer
27 January 2008 (2008-01-27)
6.66 million

When local widower Old Amos buys lace gloves for his maid Patty, Dorcas and Laura become suspicious that she may be after just his money. Robert refuses to let his children sing a song in praise of the Tories at the local church concert, which results in their being banned from the concert altogether. Robert's stubbornness incurs the wrath of his children, family and even the village.

4
"Episode 4"
Paul Rutman
John Greening
3 February 2008 (2008-02-03)
6.72 million

A strange old man arrives in Candleford looking for his estranged daughters — who turn out to be Ruby and Pearl Pratt. Horrified to see him out in public, playing scams on the local residents, the girls must decide whether they can forgive him for deserting them when they needed him most. Meanwhile, Caroline is being pursued by a bailiff collecting debts for the brewery.

5
"Episode 5"
Bill Gallagher
Charles Palmer
10 February 2008 (2008-02-10)
6.85 million

Dorcas is thrown by the surprise arrival of a new Post Office inspector, Mr Rushton, who starts to unearth anomalies in the way Dorcas runs the Post Office. Robert has been carving a decorative angel on the schoolhouse for which he is not getting paid.

6
"Episode 6"
Bill Gallagher
John Greening
17 February 2008 (2008-02-17)
6.68 million

Robert takes pity on a homeless family and brings them to stay at his house for the night. In the morning the family have departed, leaving their little daughter Polly behind. Lady Adelaide meets the girl and falls in love with her, wanting to adopt her, but Sir Tim thinks that adopting Polly would be inappropriate. Tim takes Polly to the Post Office where everyone struggles to think of a solution to the problem. Twister's delusions grow worse as he sees visions of his dead sister, and Queenie worries about his health.

7
"Episode 7"
Carolyn Bonnyman
Marc Jobst
24 February 2008 (2008-02-24)
6.70 million

The residents rally around Susan Braby when they realise her husband Sam has hit her. Meanwhile, Timothy commissions Matthew to make new gates for the manor, Adelaide becomes frustrated with how much time Tim is spending with Dorcas and decides to cancel the order for the gates, and Laura brings Phillip home for tea.

8
"Episode 8"
Gaby Chiappe
Marc Jobst
2 March 2008 (2008-03-02)
6.48 million

A violent storm hits Lark Rise and Candleford, and the arrival of a new teacher, Mr Delafield, causes divisions in the two communities. Mr Delafield's radical views raise plenty of eyebrows in Candleford, while in Lark Rise he endears himself to the residents. When Dorcas delivers some books to Mr Delafield they initially rub each other up the wrong way, but this tension soon turns to chemistry.

9
"Episode 9"
Bill Gallagher
John Greening
9 March 2008 (2008-03-09)
6.21 million

Queenie finds a beautiful embroidered panel on a grave that has the residents of Lark Rise and Candleford intrigued. Twister starts dreaming of everything he could buy if they sold the panel, while Dorcas and Sir Tim set about getting to the bottom of the mystery of who created it. Alf and Phillip's rivalry continues.

10
"Episode 10"
Bill Gallagher
John Greening
23 March 2008 (2008-03-23)
6.25 million

It is Zillah's birthday and all her friends and locals visit the post office for a party. Tensions mount between Dorcas and Sir Tim as painful truths about the past begin to surface and Dorcas decides to sell the post office. Phillip becomes increasingly possessive of Laura and she expresses doubts about their relationship.

text: Series 2 (2008–2009)[edit]

text:
#
Episode
Writer
Director
Original air date
Viewing figure

11
"Episode 1" (75-minute Christmas special)
Bill Gallagher
Alan Grint
21 December 2008 (2008-12-21)
6.58 million

Lark Rise and Candleford are transformed as the inhabitants prepare for the Christmas festivities. However, loyalties are tested as the arrival of the ghost of a ragged, bare-footed young woman drives residents to speak difficult truths amid the gift giving and carol singing.

12
"Episode 2"
Bill Gallagher
Alan Grint
4 January 2009 (2009-01-04)
6.53 million

James Dowland is the new man in town who takes the woes of the Lark Rise tenants under his wing. He also takes the heart of Dorcas Lane into his keeping, while putting Candleford on the map with the opening of a new hotel. Robert Timmins is suspicious of Dowland's motives, and is less than accepting of his financial help. Emma Timmins and the other Lark Rise tenants are, however, more than happy to see the return of a once Lark Rise boy. Meanwhile, Dorcas has her own heart strings pulled with her new maid, Minnie. Minnie can do no right; she means well, but with her troubled past she struggles to contain her excitement, testing Dorcas and those around her to the end.

13
"Episode 3"
Bill Gallagher
Alan Grint
11 January 2009 (2009-01-11)
6.13 million

Battling with conflicting emotions towards new arrival James Dowland, Dorcas Lane sets out to defeat the dashing property developer in the parish council elections. Meanwhile, the grind of making ends meet in Lark Rise proves too much for Robert and Emma Timmins, and Robert's reluctance to change grows stronger.

14
"Episode 4"
Carolyn Bonnyman
Maurice Phillips
18 January 2009 (2009-01-18)
6.49 million

The death of Miss Ellison's father unites the communities of Lark Rise and Candleford, but amid the sadness Miss Ellison is confronted by her brother George, whom she blames for her father's death. Overwhelmed with grief, Miss Ellison is oblivious to Thomas Brown's affections for her and his desire for her hand in marriage. Eventually Thomas assists in effecting a reconciliation between brother and sister.

15
"Episode 5"
Bill Gallagher
Julian Holmes
25 January 2009 (2009-01-25)
6.31 million

Time rests heavy on the residents of Lark Rise and Candleford, as baby Annie Timmins stirs up emotions of days gone by and loves yet to be found. And with Emma Timmins feeling the strains of family life, Dorcas Lane offers to lend a helping hand, unaware of the consequences that her generosity will bring. Meanwhile, newcomer Fisher Bloom arrives to build the candleford clock on Mr Dowland's orders, and stirs up mixed feelings in Laura.

16
"Episode 6"
Gaby Chiappe
Moira Armstrong
1 February 2009 (2009-02-01)
6.54 million

Lark Rise and Candleford rally round to show support for Laura's new role in the post office when Dorcas Lane is taken ill, but Laura feels pressure mounting when anonymous letters begin to arrive. Minnie sees the delivery of one of the letters, and fears that her past is catching up with her. Dorcas and Laura help Minnie to escape the threat presented by her brutal father.

17
"Episode 7"
Gaby Chiappe
Sue Tully
8 February 2009 (2009-02-08)
6.14 million

Lark Rise and Candleford anticipate with the inauguration of a clock, paid for by James Dowland. But when Robert Timmins loses his stonemason's tools, his means to work is lost, and there is a possibility that Fisher Bloom may leave Candleford unless Laura can find a way to stop him.

18
"Episode 8"
Kate Gartside
Alan Grint
15 February 2009 (2009-02-15)
6.20 million

The hot summer brings a surprise visitor to Candleford in the form of Celestia Brice Coulson, who stays at the Golden Lion Hotel and becomes acquainted with Dorcas Lane. Dorcas has other things on her mind, however, when she begins 'walking out' with James Dowland. And in Lark Rise, Emma's father, Old Edmund, arrives for his birthday. But problems arise when Emma asks him to live with them permanently.

19
"Episode 9"
Kate Gartside
David Tucker
22 February 2009 (2009-02-22)
6.32 million

A feud between Lark Rise and the neighbouring village of Fordlow has been simmering for three generations, but it takes young love to bring the two communities together and save the day. In Candleford, the path of true love runs less smoothly for Thomas and Miss Ellison; will they ever set the date for the wedding?

20
"Episode 10"
Carolyn Bonnyman
Patrick Lau
1 March 2009 (2009-03-01)
6.34 million

Every autumn, Constable Patterson is used to his wife taking to her bed with a mysterious illness. But this year is different, as she gives him permission to seek a new wife. The constable has no intention of doing any such thing, until a Pratt sister in distress sets his heart soaring; however, the other sister grows jealous and angry, especially when her sister is presented with a very unusual present.

21
"Episode 11"
Gaby Chiappe
Paul Marcus
8 March 2009 (2009-03-08)
6.78 million

A sudden storm reveals a secret romance, but also makes the address on a letter indecipherable. When Dorcas pursues the identity of the letter's recipient, she reveals another secret: a child, kept hidden even from his own father.

22
"Episode 12"
Bill Gallagher
Moira Armstrong
15 March 2009 (2009-03-15)
6.47 million

James Dowland is confined to his hospital bed when his son arrives in Candleford, and Dorcas welcomes the boy into the post office, doing everything she can to make him feel at home. But this causes a great deal of turmoil when James is released from hospital to be reunited with his son.

text: Series 3 (2010)[edit]

text:
#
Episode
Writer
Director
Original air date
Viewing figure

23
"Episode 1"
Bill Gallagher
Sue Tully
10 January 2010 (2010-01-10)
7.49 million

A young journalist, Daniel Parish, arrives in Lark Rise with exciting news for the Timmins family: Emma is set to inherit a fortune, enough to move the family to a big house in Candleford. Daniel plans to write their rags to riches story for his newspaper, but Dorcas is suspicious of his motives, and when the article is published, it sends shockwaves through the community.

24
"Episode 2"
Bill Gallagher
David Tucker
17 January 2010 (2010-01-17)
7.07 million

The Bishop is coming to consecrate the church font and Thomas cannot contain his excitement. But when a Lark Rise tree starts to 'bleed', the hamlet becomes rife with talk of witchcraft, and Thomas is horrified. Dorcas loses her composure and makes a blunder with terrible consequences for Pearl and Ruby. Also, Laura is thrown off balance when Daniel returns to try to win back her affections — but first he has to get around an angry Robert and Emma.

25
"Episode 3"
Gaby Chiappe
Patrick Lau
24 January 2010 (2010-01-24)
6.94 million

Alf throws a party to celebrate moving into a cottage of his own. He entertains his guests with a new song, and its haunting words have a profound effect on all of them. Edmund rebels against his parents; Thomas and Margaret have their first marital tiff; and Dorcas's plans to prepare Minnie for marriage and motherhood backfire terribly.

26
"Episode 4"
Gaby Chiappe
Patrick Lau
31 January 2010 (2010-01-31)
6.82 million

It's harvest time — the most important time of the year in Lark Rise, when everyone helps to bring in the wheat that will feed them through winter. So when an epidemic hits, it couldn't come at a worse time — with so many sick, how will they gather the wheat and prevent a winter of starvation? For Lark Rise, help comes from an unlikely source. But just when it looks as though their problems are solved, they discover the worst is yet to come.

27
"Episode 5"
Bill Gallagher
Moira Armstrong
7 February 2010 (2010-02-07)
6.98 million

There's a mystery in town as Mr Reppington takes residence in the Golden Lion but remains firmly isolated from the world, and Dorcas Lane is determined to find out why. Emma Timmins fears that the romance has gone out of her marriage and worries over a possible secret admirer, whilst Daniel Parish believes there may be more to Mr Reppington than meets the eye, not least a story that could make his career. Meanwhile, Ruby Pratt agonises over whether she should at last leave Candleford to meet her suitor in Pontefract, but cannot face telling her sister Pearl.

28
"Episode 6"
Bill Gallagher
Sue Tully
14 February 2010 (2010-02-14)
7.02 million

Daniel has opened a newspaper in Candleford and is on the look out for a big story. So when old Peg Leg, a Crimean War veteran, arrives for his annual visit to the Timmins', and Daniel learns he has received no war pension, he starts a newspaper campaign against this injustice. But just as Peg Leg's plight looks set to become a national cause celebre, Emma learns that he is not all he seems, a discovery that threatens to break hearts and destroy Daniel's new venture.

29
"Episode 7"
Bill Gallagher
Paul Seed
21 February 2010 (2010-02-21)
6.83 million

The locals are rehearsing for their annual production of St George and the Dragon when they hear rumours that Sir Timothy has returned. They are thrilled at the prospect of performing it for the squire himself, but with the play fast approaching and no sign of Sir Timothy, Dorcas decides to pay him a visit. She finds only Lady Adelaide. As the two women come face to face they are forced to confront their shared history, learning more about each other than they could have imagined.

30
"Episode 8"
Rachel Bennette
David Innes Edwards
28 February 2010 (2010-02-28)
6.88 million

Pearl is in a state of panic. She has received a dressmaking commission which could save her ailing business, but without Ruby, there is no way she can do the work in time. So when Enid, a talented seamstress, arrives in Candleford looking for a job, it seems Pearl's prayers have been answered. Pearl and Enid form an instant bond, based on mutual admiration and respect. But when Pearl discovers the seamstress is not who she says she is, she is forced to choose between their friendship and her deepest prejudices.

31
"Episode 9"
Bill Gallagher
Sue Tully
7 March 2010 (2010-03-07)
6.61 million

When the Lark Rise school loses its teacher, Emma steps in and discovers a talent she never knew she had. But Margaret also covets the role of schoolteacher, and the two women become rivals for the job. Over in Candleford, Thomas and Dorcas are at odds. The postman is agitating for better working conditions, and Dorcas isn't taking it well.

32
"Episode 10"
Bill Gallagher
Patrick Lau
14 March 2010 (2010-03-14)
6.33 million

When the local Lark Rise gossip Mrs Mullins discovers her daughter Emily is pregnant, she leaps to the conclusion that Daniel is the father. Everyone, including Laura, rallies round to defend him. But when Daniel's behaviour starts to arouse suspicion, and people begin to doubt him, Dorcas is determined to uncover the truth.

33
"Episode 11"
Bill Gallagher
Patrick Lau
21 March 2010 (2010-03-21)
6.39 million

Mischief Night is approaching and the folks of Lark Rise and Candleford are excitedly planning tricks to play on their neighbours. But Laura is in no mood for silly pranks — Fisher Bloom has returned, intent on winning her back, and it has thrown her feelings for Daniel into turmoil.

34
"Episode 12"
Bill Gallagher
Sue Tully
28 March 2010 (2010-03-28)
6.51 million

When the postmaster at Inglestone, with an old score to settle, tries to force Dorcas into selling up, she is faced with the heartbreaking prospect of losing her home and denying Sydney his dream of running the post office one day.

text: Series 4 (2011)[edit]

text:
#
Episode
Writer
Director
Original air date
Viewing figure

35
"Episode 1"
Bill Gallagher
Sue Tully
9 January 2011 (2011-01-09)
7.68 million

Gabriel Cochrane, the once-wealthy owner of a large iron foundry arrives in Candleford. The bank has repossessed his home and business, his young wife has died, and Gabriel finds himself looking for a new start. The people of Candleford take him to their hearts, and Dorcas offers him a job and a home. But will their kindness be enough to save him, or will he let his vendetta against the bank, and his grief over his dead wife, prevent him rebuilding his fortunes and finding happiness again?

36
"Episode 2"
Bill Gallagher
Sue Tully
16 January 2011 (2011-01-16)
7.31 million

When Daniel announces that his newspaper is launching a poetry competition, it sends the inhabitants of Candleford into a frenzy of creative excitement. Laura has high hopes of taking home the trophy and begins writing feverishly; Pearl indulges in plagiarism after her own efforts are found wanting; and even Margaret embarks upon an epic poem based on her husband’s postal rounds.

37
"Episode 3"
Bill Gallagher
Sue Tully
23 January 2011 (2011-01-23)
7.02 million

Thomas is euphoric when he lands the job of organising the church bazaar. But his joy soon evaporates when the vicar falls ill, and the controversial and free-thinking curate Reverend Marley takes charge. Thomas is convinced that Marley is evil incarnate, and when he comes across a snake on his postal rounds, he sees it as a sign that the devil is indeed amongst them.

38
"Episode 4"
Rachel Bennette
Patrick Lau
30 January 2011 (2011-01-30)
6.90 million

The Fair has come to town, and the locals are celebrating - Alf has been crowned King of the Fair, while Queenie has won a whole Berkshire pig! The Lark Risers start fattening up the pig in preparation for a sumptuous pig feast, but Twister cannot resist the temptation of selling off-cuts of the animal to the people of Candleford. At the post office, Gabriel is proving to be a less than perfect house guest; can Dorcas adapt to having a man under her roof? And will Twister survive the wrath of Queenie when she discovers he has sold her pig from under her?

39
"Episode 5"
Bill Gallagher
Sue Tully
6 February 2011 (2011-02-06)
6.96 million

Daniel is planning a cricket match against a neighbouring village team, who he is convinced cheated in their last match. He is determined to restore Candleford's honour, but most of Daniel's regular players are away, and the men of Lark Rise are cricketing novices. A humiliating defeat looks certain, until Daniel discovers that the finest batsman in the county is right under his nose. The only problem is, his batsman is a batswoman, and the rules state women cannot play.

40
"Episode 6"
Bill Gallagher
Sue Tully
13 February 2011 (2011-02-13)
7.01 million

Gabriel has finally completed the machine which he hopes will restore his fortunes, and farmers are soon clamouring to buy his ingenious invention. Dorcas is delighted for him, until she realises it could mean his departure from Candleford. Meanwhile, Caroline has returned to Lark Rise, and Minnie assumes it's only a matter of time before Alf comes to propose, now that his ma is back to look after her children. But will Caroline settle this time, and allow Alf his freedom? And how will Gabriel react to a surprising admission from Dorcas?

text: Cancellation[edit]

text: It was announced on 22 January 2011 that the show would not be returning for a fifth series.[4] The decision caused viewer complaints, prompting BBC One controller Danny Cohen to say, "Lark Rise to Candleford has been a truly wonderful part of the BBC One schedule and we are incredibly grateful to writer Bill Gallagher and the team. But we feel the time is right to make room for new dramas which we hope will be taken to the nation's hearts in the same way."[10]

text: Following that announcement, many viewers took to setting up and signing online campaigns to see the show recommissioned.[11] In response, Ben Stephenson of the BBC finally announced the decision was based on the departure of writer and executive producer Bill Gallagher, whose "creative energy" was considered essential to the series.[12]

text: DVD and Blu-ray releases[edit]

text:
DVD release
Release date
Blu-ray release
Release date
No of discs
No of episodes

The Complete First Series
7 April 2008
The Complete First Series
20 April 2009
4
10

The Complete Second Series
20 April 2009
The Complete Second Series
26 April 2010
4
12

The Complete Series 1–2
11 January 2010
N/A
N/A
1
22

The Complete Third Series
26 April 2010
The Complete Third Series
26 April 2010
4
12

The Complete Series 1–3
26 April 2010
N/A
N/A
1
34

The Complete Fourth Series
7 March 2011
The Complete Fourth Series
TBA
1
6

The Complete Series 1–4
7 March 2011
The Complete Series 1–4
TBA
14
40


document_title: Periodic table

question_text: how many are the elements of the periodic table

question_tokens: how many are the elements of the periodic table

text: Periodic table

text: Overview

text: vte

text:
Group

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

Alkali metals

Alkaline earth metals

Pnictogens

Chalcogens

Halogens

Noble gases

Period
1

Hydrogen1H7000100800000000000♠1.008

Helium2He7000400260000000000♠4.0026

2

Lithium3Li7000694000000000000♠6.94

Beryllium4Be7000901220000000000♠9.0122

Boron5B7001108100000000000♠10.81

Carbon6C7001120110000000000♠12.011

Nitrogen7N7001140070000000000♠14.007

Oxygen8O7001159990000000000♠15.999

Fluorine9F7001189980000000000♠18.998

Neon10Ne7001201800000000000♠20.180

3

Sodium11Na7001229899999999999♠22.990

Magnesium12Mg7001243050000000000♠24.305

Aluminium13Al7001269820000000000♠26.982

Silicon14Si7001280850000000000♠28.085

Phosphorus15P7001309740000000000♠30.974

Sulfur16S7001320600000000000♠32.06

Chlorine17Cl7001354500000000000♠35.45

Argon18Ar7001399480000000000♠39.948

4

Potassium19K7001390980000000000♠39.098

Calcium20Ca7001400780000000000♠40.078

Scandium21Sc7001449560000000000♠44.956

Titanium22Ti7001478670000000000♠47.867

Vanadium23V7001509420000000000♠50.942

Chromium24Cr7001519960000000000♠51.996

Manganese25Mn7001549380000000000♠54.938

Iron26Fe7001558450000000000♠55.845

Cobalt27Co7001589330000000000♠58.933

Nickel28Ni7001586930000000000♠58.693

Copper29Cu7001635460000000000♠63.546

Zinc30Zn7001653800000000000♠65.38

Gallium31Ga7001697230000000000♠69.723

Germanium32Ge7001726300000000000♠72.630

Arsenic33As7001749220000000000♠74.922

Selenium34Se7001789710000000000♠78.971

Bromine35Br7001799040000000000♠79.904

Krypton36Kr7001837980000000000♠83.798

5

Rubidium37Rb7001854680000000000♠85.468

Strontium38Sr7001876200000000000♠87.62

Yttrium39Y7001889060000000000♠88.906

Zirconium40Zr7001912240000000000♠91.224

Niobium41Nb7001929060000000000♠92.906

Molybdenum42Mo7001959500000000000♠95.95

Technetium43Tc[98]

Ruthenium44Ru7002101070000000000♠101.07

Rhodium45Rh7002102910000000000♠102.91

Palladium46Pd7002106420000000000♠106.42

Silver47Ag7002107870000000000♠107.87

Cadmium48Cd7002112410000000000♠112.41

Indium49In7002114820000000000♠114.82

Tin50Sn7002118710000000000♠118.71

Antimony51Sb7002121760000000000♠121.76

Tellurium52Te7002127600000000000♠127.60

Iodine53I7002126900000000000♠126.90

Xenon54Xe7002131289999999999♠131.29

6

Caesium55Cs7002132910000000000♠132.91

Barium56Ba7002137330000000000♠137.33

Lanthanum57La7002138910000000000♠138.91

Hafnium72Hf7002178490000000000♠178.49

Tantalum73Ta7002180950000000000♠180.95

Tungsten74W7002183840000000000♠183.84

Rhenium75Re7002186210000000000♠186.21

Osmium76Os7002190230000000000♠190.23

Iridium77Ir7002192220000000000♠192.22

Platinum78Pt7002195080000000000♠195.08

Gold79Au7002196970000000000♠196.97

Mercury80Hg7002200590000000000♠200.59

Thallium81Tl7002204380000000000♠204.38

Lead82Pb7002207200000000000♠207.2

Bismuth83Bi7002208980000000000♠208.98

Polonium84Po[209]

Astatine85At[210]

Radon86Rn[222]

7

Francium87Fr[223]

Radium88Ra[226]

Actinium89Ac[227]

Rutherfordium104Rf[267]

Dubnium105Db[268]

Seaborgium106Sg[269]

Bohrium107Bh[270]

Hassium108Hs[270]

Meitnerium109Mt[278]

Darmstadtium110Ds[281]

Roentgenium111Rg[282]

Copernicium112Cn[285]

Nihonium113Nh[286]

Flerovium114Fl[289]

Moscovium115Mc[290]

Livermorium116Lv[293]

Tennessine117Ts[294]

Oganesson118Og[294]

Cerium58Ce7002140120000000000♠140.12

Praseodymium59Pr7002140910000000000♠140.91

Neodymium60Nd7002144240000000000♠144.24

Promethium61Pm[145]

Samarium62Sm7002150360000000000♠150.36

Europium63Eu7002151960000000000♠151.96

Gadolinium64Gd7002157250000000000♠157.25

Terbium65Tb7002158930000000000♠158.93

Dysprosium66Dy7002162500000000000♠162.50

Holmium67Ho7002164930000000000♠164.93

Erbium68Er7002167260000000000♠167.26

Thulium69Tm7002168930000000000♠168.93

Ytterbium70Yb7002173050000000000♠173.05

Lutetium71Lu7002174970000000000♠174.97

Thorium90Th7002232040000000000♠232.04

Protactinium91Pa7002231040000000000♠231.04

Uranium92U7002238030000000000♠238.03

Neptunium93Np[237]

Plutonium94Pu[244]

Americium95Am[243]

Curium96Cm[247]

Berkelium97Bk[247]

Californium98Cf[251]

Einsteinium99Es[252]

Fermium100Fm[257]

Mendelevium101Md[258]

Nobelium102No[259]

Lawrencium103Lr[266]

text: 1 (red)=Gas 3 (black)=Solid 80 (green)=Liquid 109 (gray)=Unknown Color of the atomic number shows state of matter (at 0 °C and 1 atm)

text:
Ca: 7001400780000000000♠40.078 — Formal short value, rounded (no uncertainty)[5]
Po: [209] — mass number of the most stable isotope

text: Background color shows subcategory in the metal–metalloid–nonmetal trend:

text:
Metal

Metalloid

Nonmetal

Unknownchemicalproperties

Alkali metal

Alkaline earth metal

Lanthanide

Actinide

Transition metal

Post-transition metal

Reactive nonmetal

Noble gas

text: Each chemical element has a unique atomic number (Z) representing the number of protons in its nucleus.[n 2] Most elements have differing numbers of neutrons among different atoms, with these variants being referred to as isotopes. For example, carbon has three naturally occurring isotopes: all of its atoms have six protons and most have six neutrons as well, but about one per cent have seven neutrons, and a very small fraction have eight neutrons. Isotopes are never separated in the periodic table; they are always grouped together under a single element. Elements with no stable isotopes have the atomic masses of their most stable isotopes, where such masses are shown, listed in parentheses.[6]

text: In the standard periodic table, the elements are listed in order of increasing atomic number Z (the number of protons in the nucleus of an atom). A new row (period) is started when a new electron shell has its first electron. Columns (groups) are determined by the electron configuration of the atom; elements with the same number of electrons in a particular subshell fall into the same columns (e.g. oxygen and selenium are in the same column because they both have four electrons in the outermost p-subshell). Elements with similar chemical properties generally fall into the same group in the periodic table, although in the f-block, and to some respect in the d-block, the elements in the same period tend to have similar properties, as well. Thus, it is relatively easy to predict the chemical properties of an element if one knows the properties of the elements around it.[7]

text: As of  2016[update], the periodic table has 118 confirmed elements, from element 1 (hydrogen) to 118 (oganesson). Elements 113, 115, 117 and 118, the most recent discoveries, were officially confirmed by the International Union of Pure and Applied Chemistry (IUPAC) in December 2015. Their proposed names, nihonium (Nh), moscovium (Mc), tennessine (Ts) and oganesson (Og) respectively, were announced by the IUPAC in June 2016 and made official in November 2016.[8][9][10][11]

text: The first 94 elements occur naturally; the remaining 24, americium to oganesson (95–118), occur only when synthesized in laboratories. Of the 94 naturally occurring elements, 83 are primordial and 11 occur only in decay chains of primordial elements.[3] No element heavier than einsteinium (element 99) has ever been observed in macroscopic quantities in its pure form, nor has astatine (element 85); francium (element 87) has been only photographed in the form of light emitted from microscopic quantities (300,000 atoms).[12]

text: Grouping methods

text: Groups

text: A group or family is a vertical column in the periodic table. Groups usually have more significant periodic trends than periods and blocks, explained below. Modern quantum mechanical theories of atomic structure explain group trends by proposing that elements within the same group generally have the same electron configurations in their valence shell.[13] Consequently, elements in the same group tend to have a shared chemistry and exhibit a clear trend in properties with increasing atomic number.[14] In some parts of the periodic table, such as the d-block and the f-block, horizontal similarities can be as important as, or more pronounced than, vertical similarities.[15][16][17]

text: Under an international naming convention, the groups are numbered numerically from 1 to 18 from the leftmost column (the alkali metals) to the rightmost column (the noble gases).[18] Previously, they were known by roman numerals. In America, the roman numerals were followed by either an "A" if the group was in the s- or p-block, or a "B" if the group was in the d-block. The roman numerals used correspond to the last digit of today's naming convention (e.g. the group 4 elements were group IVB, and the group 14 elements were group IVA). In Europe, the lettering was similar, except that "A" was used if the group was before group 10, and "B" was used for groups including and after group 10. In addition, groups 8, 9 and 10 used to be treated as one triple-sized group, known collectively in both notations as group VIII. In 1988, the new IUPAC naming system was put into use, and the old group names were deprecated.[19]

text: Some of these groups have been given trivial (unsystematic) names, as seen in the table below, although some are rarely used. Groups 3–10 have no trivial names and are referred to simply by their group numbers or by the name of the first member of their group (such as "the scandium group" for group 3), since they display fewer similarities and/or vertical trends.[18]

text: Elements in the same group tend to show patterns in atomic radius, ionization energy, and electronegativity. From top to bottom in a group, the atomic radii of the elements increase. Since there are more filled energy levels, valence electrons are found farther from the nucleus. From the top, each successive element has a lower ionization energy because it is easier to remove an electron since the atoms are less tightly bound. Similarly, a group has a top-to-bottom decrease in electronegativity due to an increasing distance between valence electrons and the nucleus.[20] There are exceptions to these trends: for example, in group 11, electronegativity increases farther down the group.[21]

text: vte

text:
IUPAC group

1

2

3a

a

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

Mendeleev (I–VIII)

IA

IIA

IIIB

IVB

VB

VIB

VIIB

VIIIB

IB

IIB

IIIB

IVB

VB

VIB

VIIB

b

CAS (US, A-B-A)

IA

IIA

IIIB

IVB

VB

VIB

VIIB

VIIIB

IB

IIB

IIIA

IVA

VA

VIA

VIIA

VIIIA

old IUPAC (Europe, A-B)

IA

IIA

IIIA

IVA

VA

VIA

VIIA

VIIIB

IB

IIB

IIIB

IVB

VB

VIB

VIIB

0

Trivial name

Alkali metals

Alkaline earth metalsr

Coinage metals

Triels

Tetrels

Pnictogensr

Chalcogensr

Halogensr

Noble gasesr

Name by elementr

Lithium group

Beryllium group

Scandium group

Titanium group

Vanadium group

Chromium group

Manganese group

Iron group

Cobalt group

Nickel group

Copper group

Zinc group

Boron group

Carbon group

Nitrogen group

Oxygen group

Fluorine group

Helium or Neon group

Period 1

h H h

He

Period 2

Li

Be

B

C

N

O

F

Ne

Period 3

Na

Mg

Al

Si

P

S

Cl

Ar

Period 4

K

Ca

Sc

Ti

V

Cr

Mn

Fe

Co

Ni

Cu

Zn

Ga

Ge

As

Se

Br

Kr

Period 5

Rb

Sr

Y

Zr

Nb

Mo

Tc

Ru

Rh

Pd

Ag

Cd

In

Sn

Sb

Te

I

Xe

Period 6

Cs

Ba

La

Ce–Lu

Hf

Ta

W

Re

Os

Ir

Pt

Au

Hg

Tl

Pb

Bi

Po

At

Rn

Period 7

Fr

Ra

Ac

Th–Lr

Rf

Db

Sg

Bh

Hs

Mt

Ds

Rg

Cn

Nh

Fl

Mc

Lv

Ts

Og

text: Periods

text: A period is a horizontal row in the periodic table. Although groups generally have more significant periodic trends, there are regions where horizontal trends are more significant than vertical group trends, such as the f-block, where the lanthanides and actinides form two substantial horizontal series of elements.[23]

text: Elements in the same period show trends in atomic radius, ionization energy, electron affinity, and electronegativity. Moving left to right across a period, atomic radius usually decreases. This occurs because each successive element has an added proton and electron, which causes the electron to be drawn closer to the nucleus.[24] This decrease in atomic radius also causes the ionization energy to increase when moving from left to right across a period. The more tightly bound an element is, the more energy is required to remove an electron. Electronegativity increases in the same manner as ionization energy because of the pull exerted on the electrons by the nucleus.[20] Electron affinity also shows a slight trend across a period. Metals (left side of a period) generally have a lower electron affinity than nonmetals (right side of a period), with the exception of the noble gases.[25]

text: Blocks

text: Specific regions of the periodic table can be referred to as blocks in recognition of the sequence in which the electron shells of the elements are filled. Each block is named according to the subshell in which the "last" electron notionally resides.[26][n 3] The s-block comprises the first two groups (alkali metals and alkaline earth metals) as well as hydrogen and helium. The p-block comprises the last six groups, which are groups 13 to 18 in IUPAC group numbering (3A to 8A in American group numbering) and contains, among other elements, all of the metalloids. The d-block comprises groups 3 to 12 (or 3B to 2B in American group numbering) and contains all of the transition metals. The f-block, often offset below the rest of the periodic table, has no group numbers and comprises lanthanides and actinides.[27]

text: Metals, metalloids and nonmetals

text: According to their shared physical and chemical properties, the elements can be classified into the major categories of metals, metalloids and nonmetals. Metals are generally shiny, highly conducting solids that form alloys with one another and salt-like ionic compounds with nonmetals (other than noble gases). A majority of nonmetals are coloured or colourless insulating gases; nonmetals that form compounds with other nonmetals, feature covalent bonding. In between metals and nonmetals are metalloids, which have intermediate or mixed properties.[28]

text: Metal and nonmetals can be further classified into subcategories that show a gradation from metallic to non-metallic properties, when going left to right in the rows. The metals may be subdivided into the highly reactive alkali metals, through the less reactive alkaline earth metals, lanthanides and actinides, via the archetypal transition metals, and ending in the physically and chemically weak post-transition metals. Nonmetals may be simply subdivided into the polyatomic nonmetals, being nearer to the metalloids and show some incipient metallic character; the essentially nonmetallic diatomic nonmetals, nonmetallic and the almost completely inert, monatomic noble gases. Specialized groupings such as refractory metals and noble metals, are examples of subsets of transition metals, also known[29] and occasionally denoted.[30]

text: Placing elements into categories and subcategories based just on shared properties is imperfect. There is a large disparity of properties within each category with notable overlaps at the boundaries, as is the case with most classification schemes.[31] Beryllium, for example, is classified as an alkaline earth metal although its amphoteric chemistry and tendency to mostly form covalent compounds are both attributes of a chemically weak or post-transition metal. Radon is classified as a nonmetallic noble gas yet has some cationic chemistry that is characteristic of metals. Other classification schemes are possible such as the division of the elements into mineralogical occurrence categories, or crystalline structures. Categorizing the elements in this fashion dates back to at least 1869 when Hinrichs[32] wrote that simple boundary lines could be placed on the periodic table to show elements having shared properties, such as metals, nonmetals, or gaseous elements.

text: Periodic trends and patterns

text: Electron configuration

text: The electron configuration or organisation of electrons orbiting neutral atoms shows a recurring pattern or periodicity. The electrons occupy a series of electron shells (numbered 1, 2, and so on). Each shell consists of one or more subshells (named s, p, d, f and g). As atomic number increases, electrons progressively fill these shells and subshells more or less according to the Madelung rule or energy ordering rule, as shown in the diagram. The electron configuration for neon, for example, is 1s2 2s2 2p6. With an atomic number of ten, neon has two electrons in the first shell, and eight electrons in the second shell; there are two electrons in the s subshell and six in the p subshell. In periodic table terms, the first time an electron occupies a new shell corresponds to the start of each new period, these positions being occupied by hydrogen and the alkali metals.[33][34]

text: Since the properties of an element are mostly determined by its electron configuration, the properties of the elements likewise show recurring patterns or periodic behaviour, some examples of which are shown in the diagrams below for atomic radii, ionization energy and electron affinity. It is this periodicity of properties, manifestations of which were noticed well before the underlying theory was developed, that led to the establishment of the periodic law (the properties of the elements recur at varying intervals) and the formulation of the first periodic tables.[33][34]

text: Atomic radii

text: Atomic radii vary in a predictable and explainable manner across the periodic table. For instance, the radii generally decrease along each period of the table, from the alkali metals to the noble gases; and increase down each group. The radius increases sharply between the noble gas at the end of each period and the alkali metal at the beginning of the next period. These trends of the atomic radii (and of various other chemical and physical properties of the elements) can be explained by the electron shell theory of the atom; they provided important evidence for the development and confirmation of quantum theory.[35]

text: The electrons in the 4f-subshell, which is progressively filled across the lanthanide series, are not particularly effective at shielding the increasing nuclear charge from the sub-shells further out. The elements immediately following the lanthanides have atomic radii that are smaller than would be expected and that are almost identical to the atomic radii of the elements immediately above them.[36] Hence hafnium has virtually the same atomic radius (and chemistry) as zirconium, and tantalum has an atomic radius similar to niobium, and so forth. This is known as the lanthanide contraction. The effect of the lanthanide contraction is noticeable up to platinum (element 78), after which it is masked by a relativistic effect known as the inert pair effect.[37] The d-block contraction, which is a similar effect between the d-block and p-block, is less pronounced than the lanthanide contraction but arises from a similar cause.[36]

text: Ionization energy

text: The first ionization energy is the energy it takes to remove one electron from an atom, the second ionization energy is the energy it takes to remove a second electron from the atom, and so on. For a given atom, successive ionization energies increase with the degree of ionization. For magnesium as an example, the first ionization energy is 738 kJ/mol and the second is 1450 kJ/mol. Electrons in the closer orbitals experience greater forces of electrostatic attraction; thus, their removal requires increasingly more energy. Ionization energy becomes greater up and to the right of the periodic table.[37]

text: Large jumps in the successive molar ionization energies occur when removing an electron from a noble gas (complete electron shell) configuration. For magnesium again, the first two molar ionization energies of magnesium given above correspond to removing the two 3s electrons, and the third ionization energy is a much larger 7730 kJ/mol, for the removal of a 2p electron from the very stable neon-like configuration of Mg2+. Similar jumps occur in the ionization energies of other third-row atoms.[37]

text: Electronegativity

text: Electronegativity is the tendency of an atom to attract a shared pair of electrons.[38] An atom's electronegativity is affected by both its atomic number and the distance between the valence electrons and the nucleus. The higher its electronegativity, the more an element attracts electrons. It was first proposed by Linus Pauling in 1932.[39] In general, electronegativity increases on passing from left to right along a period, and decreases on descending a group. Hence, fluorine is the most electronegative of the elements,[n 5] while caesium is the least, at least of those elements for which substantial data is available.[21]

text: There are some exceptions to this general rule. Gallium and germanium have higher electronegativities than aluminium and silicon respectively because of the d-block contraction. Elements of the fourth period immediately after the first row of the transition metals have unusually small atomic radii because the 3d-electrons are not effective at shielding the increased nuclear charge, and smaller atomic size correlates with higher electronegativity.[21] The anomalously high electronegativity of lead, particularly when compared to thallium and bismuth, appears to be an artifact of data selection and data availability.  Methods of calculation other than the Pauling method show the normal periodic trends for these elements.[40]

text: Electron affinity

text: The electron affinity of an atom is the amount of energy released when an electron is added to a neutral atom to form a negative ion. Although electron affinity varies greatly, some patterns emerge. Generally, nonmetals have more positive electron affinity values than metals. Chlorine most strongly attracts an extra electron. The electron affinities of the noble gases have not been measured conclusively, so they may or may not have slightly negative values.[43]

text: Electron affinity generally increases across a period. This is caused by the filling of the valence shell of the atom; a group 17 atom releases more energy than a group 1 atom on gaining an electron because it obtains a filled valence shell and is therefore more stable.[43]

text: A trend of decreasing electron affinity going down groups would be expected. The additional electron will be entering an orbital farther away from the nucleus. As such this electron would be less attracted to the nucleus and would release less energy when added. In going down a group, around one-third of elements are anomalous, with heavier elements having higher electron affinities than their next lighter congenors. Largely, this is due to the poor shielding by d and f electrons. A uniform decrease in electron affinity only applies to group 1 atoms.[44]

text: Metallic character

text: The lower the values of ionization energy, electronegativity and electron affinity, the more metallic character the element has. Conversely, nonmetallic character increases with higher values of these properties.[45] Given the periodic trends of these three properties, metallic character tends to decrease going across a period (or row) and, with some irregularities (mostly) due to poor screening of the nucleus by d and f electrons, and relativistic effects,[46] tends to increase going down a group (or column or family). Thus, the most metallic elements (such as caesium and francium) are found at the bottom left of traditional periodic tables and the most nonmetallic elements (oxygen, fluorine, chlorine) at the top right. The combination of horizontal and vertical trends in metallic character explains the stair-shaped dividing line between metals and nonmetals found on some periodic tables, and the practice of sometimes categorizing several elements adjacent to that line, or elements adjacent to those elements, as metalloids.[47][48]

text: Linking or bridging groups

text:
Hydrogen

Helium

Lithium

Beryllium

Boron

Carbon

Nitrogen

Oxygen

Fluorine

Neon

Sodium

Magnesium

Aluminium

Silicon

Phosphorus

Sulfur

Chlorine

Argon

Potassium

Calcium

Scandium

Titanium

Vanadium

Chromium

Manganese

Iron

Cobalt

Nickel

Copper

Zinc

Gallium

Germanium

Arsenic

Selenium

Bromine

Krypton

Rubidium

Strontium

Yttrium

Zirconium

Niobium

Molybdenum

Technetium

Ruthenium

Rhodium

Palladium

Silver

Cadmium

Indium

Tin

Antimony

Tellurium

Iodine

Xenon

Caesium

Barium

Lanthanum

Cerium

Praseodymium

Neodymium

Promethium

Samarium

Europium

Gadolinium

Terbium

Dysprosium

Holmium

Erbium

Thulium

Ytterbium

Lutetium

Hafnium

Tantalum

Tungsten

Rhenium

Osmium

Iridium

Platinum

Gold

Mercury (element)

Thallium

Lead

Bismuth

Polonium

Astatine

Radon

Francium

Radium

Actinium

Thorium

Protactinium

Uranium

Neptunium

Plutonium

Americium

Curium

Berkelium

Californium

Einsteinium

Fermium

Mendelevium

Nobelium

Lawrencium

Rutherfordium

Dubnium

Seaborgium

Bohrium

Hassium

Meitnerium

Darmstadtium

Roentgenium

Copernicium

Nihonium

Flerovium

Moscovium

Livermorium

Tennessine

Oganesson

text: From left to right across the four blocks of the long- or 32-column form of the periodic table are a series of linking or bridging groups of elements, located approximately between each block.[49] These groups, like the metalloids, show properties in between, or that are a mixture of, groups to either side. Chemically, the group 3 elements, scandium, yttrium, lanthanum and actinium behave largely like the alkaline earth metals[50] or, more generally, s block metals[51][52] but have some of the physical properties of d block transition metals.[53] Lutetium and lawrencium, at the end of the end of the f block, may constitute another linking or bridging group. Lutetium behaves chemically as a lanthanide but shows a mix of lanthanide and transition metal physical properties.[54][55] Lawrencium, as an analogue of lutetium, would presumable display like characteristics.[n 6] The coinage metals in group 11 (copper, silver, and gold) are chemically capable of acting as either transition metals or main group metals.[58] The volatile group 12 metals, zinc, cadmium and mercury are sometimes regarded as linking the d block to the p block. Notionally they are d block elements but they have few transition metal properties and are more like their p block neighbors in group 13.[59][60] The relatively inert noble gases, in group 18, bridge the most reactive groups of elements in the periodic table—the halogens in group 17 and the alkali metals in group 1.[49]

text: History

text: First systemization attempts

text: In 1789, Antoine Lavoisier published a list of 33 chemical elements, grouping them into gases, metals, nonmetals, and earths.[61] Chemists spent the following century searching for a more precise classification scheme. In 1829, Johann Wolfgang Döbereiner observed that many of the elements could be grouped into triads based on their chemical properties. Lithium, sodium, and potassium, for example, were grouped together in a triad as soft, reactive metals. Döbereiner also observed that, when arranged by atomic weight, the second member of each triad was roughly the average of the first and the third;[62] this became known as the Law of Triads.[63] German chemist Leopold Gmelin worked with this system, and by 1843 he had identified ten triads, three groups of four, and one group of five. Jean-Baptiste Dumas published work in 1857 describing relationships between various groups of metals. Although various chemists were able to identify relationships between small groups of elements, they had yet to build one scheme that encompassed them all.[62]

text: In 1857, German chemist August Kekulé observed that carbon often has four other atoms bonded to it. Methane, for example, has one carbon atom and four hydrogen atoms.[64] This concept eventually became known as valency; different elements bond with different numbers of atoms.[65]

text: In 1862, Alexandre-Emile Béguyer de Chancourtois, a French geologist, published an early form of periodic table, which he called the telluric helix or screw. He was the first person to notice the periodicity of the elements. With the elements arranged in a spiral on a cylinder by order of increasing atomic weight, de Chancourtois showed that elements with similar properties seemed to occur at regular intervals. His chart included some ions and compounds in addition to elements. His paper also used geological rather than chemical terms and did not include a diagram; as a result, it received little attention until the work of Dmitri Mendeleev.[66]

text: In 1864, Julius Lothar Meyer, a German chemist, published a table with 44 elements arranged by valency. The table showed that elements with similar properties often shared the same valency.[67] Concurrently, English chemist William Odling published an arrangement of 57 elements, ordered on the basis of their atomic weights. With some irregularities and gaps, he noticed what appeared to be a periodicity of atomic weights among the elements and that this accorded with "their usually received groupings".[68] Odling alluded to the idea of a periodic law but did not pursue it.[69] He subsequently proposed (in 1870) a valence-based classification of the elements.[70]

text: English chemist John Newlands produced a series of papers from 1863 to 1866 noting that when the elements were listed in order of increasing atomic weight, similar physical and chemical properties recurred at intervals of eight; he likened such periodicity to the octaves of music.[71][72] This so termed Law of Octaves was ridiculed by Newlands' contemporaries, and the Chemical Society refused to publish his work.[73] Newlands was nonetheless able to draft a table of the elements and used it to predict the existence of missing elements, such as germanium.[74] The Chemical Society only acknowledged the significance of his discoveries five years after they credited Mendeleev.[75]

text: In 1867, Gustavus Hinrichs, a Danish born academic chemist based in America, published a spiral periodic system based on atomic spectra and weights, and chemical similarities. His work was regarded as idiosyncratic, ostentatious and labyrinthine and this may have militated against its recognition and acceptance.[76][77]

text: Mendeleev's table

text: Russian chemistry professor Dmitri Mendeleev and German chemist Julius Lothar Meyer independently published their periodic tables in 1869 and 1870, respectively.[78] Mendeleev's table was his first published version; that of Meyer was an expanded version of his (Meyer's) table of 1864.[79] They both constructed their tables by listing the elements in rows or columns in order of atomic weight and starting a new row or column when the characteristics of the elements began to repeat.[80]

text: The recognition and acceptance afforded to Mendeleev's table came from two decisions he made. The first was to leave gaps in the table when it seemed that the corresponding element had not yet been discovered.[81] Mendeleev was not the first chemist to do so, but he was the first to be recognized as using the trends in his periodic table to predict the properties of those missing elements, such as gallium and germanium.[82] The second decision was to occasionally ignore the order suggested by the atomic weights and switch adjacent elements, such as tellurium and iodine, to better classify them into chemical families.

text: Mendeleev published in 1869, using atomic weight to organize the elements, information determinable to fair precision in his time. Atomic weight worked well enough to allow Mendeleev to accurately predict the properties of missing elements.

text: Following the discovery, in 1911, by Ernest Rutherford of the atomic nucleus, it was proposed that the integer count of the nuclear charge is identical to the sequential place of each element in the periodic table. In 1913, Henry Moseley using X-ray spectroscopy confirmed this proposal experimentally. Moseley determined the value of the nuclear charge of each element, and showed that Mendeleev's ordering actually places the elements in sequential order by nuclear charge.[83] Nuclear charge is identical to proton count, and determines the value of the atomic number (Z) of each element. Using atomic number gives a definitive, integer-based sequence for the elements. Moseley predicted, in 1913, that the only elements still missing between aluminium (Z=13) and gold (Z=79) were Z = 43, 61, 72, and 75, all of which were later discovered. The atomic number is the absolute definition of an element, and gives a factual basis for the ordering of the periodic table. The periodic table is used to predict the properties of new synthetic elements before they are produced and studied.[84]

text: Second version and further development

text: In 1871, Mendeleev published his periodic table in a new form, with groups of similar elements arranged in columns rather than in rows, and those columns numbered I to VIII corresponding with the element's oxidation state. He also gave detailed predictions for the properties of elements he had earlier noted were missing, but should exist.[85] These gaps were subsequently filled as chemists discovered additional naturally occurring elements.[86] It is often stated that the last naturally occurring element to be discovered was francium (referred to by Mendeleev as eka-caesium) in 1939.[87] Plutonium, produced synthetically in 1940, was identified in trace quantities as a naturally occurring element in 1971.[88]

text: The popular[89] periodic table layout, also known as the common or standard form (as shown at various other points in this article), is attributable to Horace Groves Deming. In 1923, Deming, an American chemist, published short (Mendeleev style) and medium (18-column) form periodic tables.[90][n 7] Merck and Company prepared a handout form of Deming's 18-column medium table, in 1928, which was widely circulated in American schools. By the 1930s Deming's table was appearing in handbooks and encyclopaedias of chemistry. It was also distributed for many years by the Sargent-Welch Scientific Company.[91][92][93]

text: With the development of modern quantum mechanical theories of electron configurations within atoms, it became apparent that each period (row) in the table corresponded to the filling of a quantum shell of electrons. Larger atoms have more electron sub-shells, so later tables have required progressively longer periods.[94]

text: In 1945, Glenn Seaborg, an American scientist, made the suggestion that the actinide elements, like the lanthanides, were filling an f sub-level. Before this time the actinides were thought to be forming a fourth d-block row. Seaborg's colleagues advised him not to publish such a radical suggestion as it would most likely ruin his career. As Seaborg considered he did not then have a career to bring into disrepute, he published anyway. Seaborg's suggestion was found to be correct and he subsequently went on to win the 1951 Nobel Prize in chemistry for his work in synthesizing actinide elements.[95][96][n 8]

text: Although minute quantities of some transuranic elements occur naturally,[3] they were all first discovered in laboratories. Their production has expanded the periodic table significantly, the first of these being neptunium, synthesized in 1939.[97] Because many of the transuranic elements are highly unstable and decay quickly, they are challenging to detect and characterize when produced. There have been controversies concerning the acceptance of competing discovery claims for some elements, requiring independent review to determine which party has priority, and hence naming rights.[98] In 2010, a joint Russia–US collaboration at Dubna, Moscow Oblast, Russia, claimed to have synthesized six atoms of tennessine (element 117), making it the most recently claimed discovery. It, along with nihonium (element 113), moscovium (element 115), and oganesson (element 118), are the four most recently named elements, whose names all became official on 28 November 2016.[99]

text: Different periodic tables

text: The long- or 32-column table

text: The modern periodic table is sometimes expanded into its long or 32-column form by reinstating the footnoted f-block elements into their natural position between the s- and d-blocks. Unlike the 18-column form this arrangement results in "no interruptions in the sequence of increasing atomic numbers".[100] The relationship of the f-block to the other blocks of the periodic table also becomes easier to see.[101] Jensen advocates a form of table with 32 columns on the grounds that the lanthanides and actinides are otherwise relegated in the minds of students as dull, unimportant elements that can be quarantined and ignored.[102] Despite these advantages the 32-column form is generally avoided by editors on account of its undue rectangular ratio (compared to a book page ratio),[103] and the familiarity of chemists with the modern form (as introduced by Seaborg).[104]

text: Tables with different structures

text: Within 100 years of the appearance of Mendeleev's table in 1869 it has been estimated that around 700 different periodic table versions were published.[105] As well as numerous rectangular variations, other periodic table formats have been shaped, for example,[n 9] like a circle, cube, cylinder, building, spiral, lemniscate,[106] octagonal prism, pyramid, sphere, or triangle. Such alternatives are often developed to highlight or emphasize chemical or physical properties of the elements that are not as apparent in traditional periodic tables.[105]

text: A popular[107] alternative structure is that of Theodor Benfey (1960). The elements are arranged in a continuous spiral, with hydrogen at the centre and the transition metals, lanthanides, and actinides occupying peninsulas.[108]

text:
Most periodic tables are two-dimensional;[3] three-dimensional tables are known to as far back as at least 1862 (pre-dating Mendeleev's two-dimensional table of 1869). More recent examples include Courtines' Periodic Classification (1925),[109] Wringley's Lamina System (1949),[110]
Giguère's Periodic helix (1965)[111] and Dufour's Periodic Tree (1996).[112] Going one further, Stowe's Physicist's Periodic Table (1989)[113] has been described as being four-dimensional (having three spatial dimensions and one colour dimension).[114]

text: The various forms of periodic tables can be thought of as lying on a chemistry–physics continuum.[115] Towards the chemistry end of the continuum can be found, as an example, Rayner-Canham's "unruly"[116] Inorganic Chemist's Periodic Table (2002),[117] which emphasizes trends and patterns, and unusual chemical relationships and properties. Near the physics end of the continuum is Janet's Left-Step Periodic Table (1928). This has a structure that shows a closer connection to the order of electron-shell filling and, by association, quantum mechanics.[118] A somewhat similar approach has been taken by Alper,[119] albeit criticized by Eric Scerri as disregarding the need to display chemical and physical periodicity.[120] Somewhere in the middle of the continuum is the ubiquitous common or standard form of periodic table. This is regarded as better expressing empirical trends in physical state, electrical and thermal conductivity, and oxidation numbers, and other properties easily inferred from traditional techniques of the chemical laboratory.[121] Its popularity is thought to be a result of this layout having a good balance of features in terms of ease of construction and size, and its depiction of atomic order and periodic trends.[69][122]

text: vte

text:
f1

f2

f3

f4

f5

f6

f7

f8

f9

f10

f11

f12

f13

f14

d1

d2

d3

d4

d5

d6

d7

d8

d9

d10

p1

p2

p3

p4

p5

p6

s1

s2

1s

H

He

2s

Li

Be

2p 3s

B

C

N

O

F

Ne

Na

Mg

3p 4s

Al

Si

P

S

Cl

Ar

K

Ca

3d 4p 5s

Sc

Ti

V

Cr

Mn

Fe

Co

Ni

Cu

Zn

Ga

Ge

As

Se

Br

Kr

Rb

Sr

4d 5p 6s

Y

Zr

Nb

Mo

Tc

Ru

Rh

Pd

Ag

Cd

In

Sn

Sb

Te

 I

Xe

Cs

Ba

4f 5d 6p 7s

La

Ce

Pr

Nd

Pm

Sm

Eu

Gd

Tb

Dy

Ho

Er

Tm

Yb

Lu

Hf

Ta

W

Re

Os

Ir

Pt

Au

Hg

Tl

Pb

Bi

Po

At

Rn

Fr

Ra

5f 6d 7p 8s

Ac

Th

Pa

U

Np

Pu

Am

Cm

Bk

Cf

Es

Fm

Md

No

Lr

Rf

Db

Sg

Bh

Hs

Mt

Ds

Rg

Cn

Nh

Fl

Mc

Lv

Ts

Og

119

120

f-block

d-block

p-block

s-block

text: Open questions and controversies

text: Placement of hydrogen and helium

text: Simply following electron configurations, hydrogen (electronic configuration 1s1) and helium (1s2) should be placed in groups 1 and 2, above lithium (1s22s1) and beryllium (1s22s2).[26] While such a placement is common for hydrogen, it is rarely used for helium outside of the context of electron configurations: When the noble gases (then called "inert gases") were first discovered around 1900, they were known as "group 0", reflecting no chemical reactivity of these elements known at that point, and helium was placed on the top of that group, as it did share the extreme chemical inertness seen throughout the group. As the group changed its formal number, many authors continued to assign helium directly above neon, in group 18; one of the examples of such placing is the current IUPAC table.[123]

text: Hydrogen's chemical properties are not very close to those of the alkali metals, which occupy group 1. On this basis it is sometimes placed elsewhere. A common alternative is at the top of group 17[120] given hydrogen's strictly univalent and largely non-metallic chemistry, and the strictly univalent and non-metallic chemistry of fluorine (the element otherwise at the top of group 17). Sometimes, to show hydrogen has properties corresponding to both those of the alkali metals and the halogens, it is shown at the top of the two columns simultaneously.[124] Another suggestion is above carbon in group 14: placed that way, it fits well into the trends of increasing ionization potential values and electron affinity values, and is not too far from the electronegativity trend, even though hydrogen cannot show the tetravalence characteristic of the heavier group 14 elements.[125] Finally, hydrogen is sometimes placed separately from any group; this is based on its general properties being different from those of the elements in any other group. The other period 1 element, helium, is sometimes placed separately from any group as well.[126] The property that distinguishes helium from the rest of the noble gases (even though the extraordinary inertness of helium is extremely close to that of neon and argon)[127] is that in its closed electron shell, helium has only two electrons in the outermost electron orbital, while the rest of the noble gases have eight.

text: Group 3 and its elements in periods 6 and 7

text: Although scandium and yttrium are always the first two elements in group 3, the identity of the next two elements is not completely settled. They are commonly lanthanum and actinium, and less often lutetium and lawrencium. The two variants originate from historical difficulties in placing the lanthanides in the periodic table, and arguments as to where the f block elements start and end.[128][n 10][n 11] It has been claimed that such arguments are proof that, "it is a mistake to break the [periodic] system into sharply delimited blocks".[130] A third variant shows the two positions below yttrium as being occupied by the lanthanides and the actinides.

text: Chemical and physical arguments have been made in support of lutetium and lawrencium[131][132] but the majority of authors seem unconvinced.[133] Most working chemists are not aware there is any controversy.[134] In December 2015 an IUPAC project was established to make a recommendation on the matter.[135]

text: Lanthanum and actinium

text: La and Ac below Y

text: Lanthanum and actinium are commonly depicted as the remaining group 3 members.[136][n 12] It has been suggested that this layout originated in the 1940s, with the appearance of periodic tables relying on the electron configurations of the elements and the notion of the differentiating electron. The configurations of caesium, barium and lanthanum are [Xe]6s1, [Xe]6s2 and [Xe]5d16s2. Lanthanum thus has a 5d differentiating electron and this establishes it "in group 3 as the first member of the d-block for period 6".[137] A consistent set of electron configurations is then seen in group 3: scandium [Ar]3d14s2, yttrium [Kr]4d15s2 and lanthanum  [Xe]5d16s2. Still in period 6, ytterbium was assigned an electron configuration of [Xe]4f135d16s2 and lutetium [Xe]4f145d16s2, "resulting in a 4f differentiating electron for lutetium and firmly establishing it as the last member of the f-block for period 6".[137] Later spectroscopic work found that the electron configuration of ytterbium was in fact [Xe]4f146s2. This meant that ytterbium and lutetium—the latter with [Xe]4f145d16s2—both had 14 f-electrons, "resulting in a d- rather than an f- differentiating electron" for lutetium and making it an "equally valid candidate" with [Xe]5d16s2 lanthanum, for the group 3 periodic table position below yttrium.[137] Lanthanum has the advantage of incumbency since the 5d1 electron appears for the first time in its structure whereas it appears for the third time in lutetium, having also made a brief second appearance in gadolinium.[138]

text: In terms of chemical behaviour,[139] and trends going down group 3 for properties such as melting point, electronegativity and ionic radius,[140][141] scandium, yttrium, lanthanum and actinium are similar to their group 1–2 counterparts. In this variant, the number of f electrons in the most common (trivalent) ions of the f-block elements consistently matches their position in the f-block.[142] For example, the f-electron counts for the trivalent ions of the first three f-block elements are Ce 1, Pr 2 and Nd 3.[143]

text: Lutetium and lawrencium

text: Lu and Lr below Y

text: In other tables, lutetium and lawrencium are the remaining group 3 members.[n 13] Early techniques for chemically separating scandium, yttrium and lutetium relied on the fact that these elements occurred together in the so-called "yttrium group" whereas La and Ac occurred together in the "cerium group".[137] Accordingly, lutetium rather than lanthanum was assigned to group 3 by some chemists in the 1920s and 30s.[n 14] Several physicists in the 1950s and '60s favoured lutetium, in light of a comparison of several of its physical properties with those of lanthanum.[137] This arrangement, in which lanthanum is the first member of the f-block, is disputed by some authors since lanthanum lacks any f-electrons. It has been argued that this is not valid concern given other periodic table anomalies—thorium, for example, has no f-electrons yet is part of the f-block.[144] As for lawrencium, its gas phase atomic electron configuration was confirmed in 2015 as [Rn]5f147s27p1. Such a configuration represents another periodic table anomaly, regardless of whether lawrencium is located in the f-block or the d-block, as the only potentially applicable p-block position has been reserved for nihonium with its predicted configuration of [Rn]5f146d107s27p1.[145][n 15]

text: Chemically, scandium, yttrium and lutetium (and presumably lawrencium) behave like trivalent versions of the group 1–2 metals.[147] On the other hand, trends going down the group for properties such as melting point, electronegativity and ionic radius, are similar to those found among their group 4–8 counterparts.[137] In this variant, the number of f electrons in the gaseous forms of the f-block atoms usually matches their position in the f-block. For example, the f-electron counts for the first five f-block elements are La 0, Ce 1, Pr 3, Nd 4 and Pm 5.[137]

text: Lanthanides and actinides

text: Markers below Y

text:
A few authors position all thirty lanthanides and actinides in the two positions below yttrium (usually via footnote markers).
This variant emphasizes similarities in the chemistry of the 15 lanthanide elements (La–Lu), possibly at the expense of ambiguity as to which elements occupy the two group 3 positions below yttrium, and a 15-column wide f block (there can only be 14 elements in any row of the f block).[n 16]

text: Groups included in the transition metals

text: The definition of a transition metal, as given by IUPAC, is an element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell.[148] By this definition all of the elements in groups 3–11 are transition metals. The IUPAC definition therefore excludes group 12, comprising zinc, cadmium and mercury, from the transition metals category.

text: Some chemists treat the categories "d-block elements" and "transition metals" interchangeably, thereby including groups 3–12 among the transition metals. In this instance the group 12 elements are treated as a special case of transition metal in which the d electrons are not ordinarily involved in chemical bonding. The 2007 report of mercury(IV) fluoride (HgF4), a compound in which mercury would use its d electrons for bonding, has prompted some commentators to suggest that mercury can be regarded as a transition metal.[149] Other commentators, such as Jensen,[150] have argued that the formation of a compound like HgF4 can occur only under highly abnormal conditions; indeed, its existence is currently disputed. As such, mercury could not be regarded as a transition metal by any reasonable interpretation of the ordinary meaning of the term.[150]

text: Still other chemists further exclude the group 3 elements from the definition of a transition metal. They do so on the basis that the group 3 elements do not form any ions having a partially occupied d shell and do not therefore exhibit any properties characteristic of transition metal chemistry.[151] In this case, only groups 4–11 are regarded as transition metals. Though the group 3 elements show few of the characteristic chemical properties of the transition metals, they do show some of their characteristic physical properties (on account of the presence in each atom of a single d electron).[53]

text: Elements with unknown chemical properties

text: Although all elements up to oganesson have been discovered, of the elements above hassium (element 108), only copernicium (element 112), nihonium (element 113), and flerovium (element 114) have known chemical properties, and only for copernicium is there enough evidence for a conclusive categorisation at present. The other elements may behave differently from what would be predicted by extrapolation, due to relativistic effects; for example, flerovium has been predicted to possibly exhibit some noble-gas-like properties, even though it is currently placed in the carbon group.[152] The current experimental evidence still leaves open the question of whether flerovium behaves more like a metal or a noble gas.[153]

text: Further periodic table extensions

text:
Ununennium

Unbinilium

Unbiunium

Unquadquadium

Unquadpentium

Unquadhexium

Unquadseptium

Unquadoctium

Unquadennium

Unpentnilium

Unpentunium

Unpentbium

Unpenttrium

Unpentquadium

Unpentpentium

Unpenthexium

Unpentseptium

Unpentoctium

Unpentennium

Unhexnilium

Unhexunium

Unhexbium

Unhextrium

Unhexquadium

Unhexpentium

Unhexhexium

Unhexseptium

Unhexoctium

Unhexennium

Unseptnilium

Unseptunium

Unseptbium

Unbibium

Unbitrium

Unbiquadium

Unbipentium

Unbihexium

Unbiseptium

Unbioctium

Unbiennium

Untrinilium

Untriunium

Untribium

Untritrium

Untriquadium

Untripentium

Untrihexium

Untriseptium

Untrioctium

Untriennium

Unquadnilium

Unquadunium

Unquadbium

Unquadtrium

text: It is unclear whether new elements will continue the pattern of the current periodic table as period 8, or require further adaptations or adjustments. Seaborg expected the eighth period to follow the previously established pattern exactly, so that it would include a two-element s-block for elements 119 and 120, a new g-block for the next 18 elements, and 30 additional elements continuing the current f-, d-, and p-blocks, culminating in element 168, the next noble gas.[155] More recently, physicists such as Pekka Pyykkö have theorized that these additional elements do not follow the Madelung rule, which predicts how electron shells are filled and thus affects the appearance of the present periodic table. There are currently several competing theoretical models for the placement of the elements of atomic number less than or equal to 172. In all of these it is element 172, rather than element 168, that emerges as the next noble gas after oganesson, although these must be regarded as speculative as no complete calculations have been done beyond element 122.[156]

text: Element with the highest possible atomic number

text: The number of possible elements is not known. A very early suggestion made by Elliot Adams in 1911, and based on the arrangement of elements in each horizontal periodic table row, was that elements of atomic weight greater than circa 256 (which would equate to between elements 99 and 100 in modern-day terms) did not exist.[157] A higher—more recent—estimate is that the periodic table may end soon after the island of stability,[158] which is expected to centre around element 126, as the extension of the periodic and nuclides tables is restricted by proton and neutron drip lines.[159] Other predictions of an end to the periodic table include at element 128 by John Emsley,[3] at element 137 by Richard Feynman,[160] and at element 155 by Albert Khazan.[3][n 17]

text: The Bohr model exhibits difficulty for atoms with atomic number greater than 137, as any element with an atomic number greater than 137 would require 1s electrons to be travelling faster than c, the speed of light.[161] Hence the non-relativistic Bohr model is inaccurate when applied to such an element.

text: The relativistic Dirac equation has problems for elements with more than 137 protons. For such elements, the wave function of the Dirac ground state is oscillatory rather than bound, and there is no gap between the positive and negative energy spectra, as in the Klein paradox.[162] More accurate calculations taking into account the effects of the finite size of the nucleus indicate that the binding energy first exceeds the limit for elements with more than 173 protons. For heavier elements, if the innermost orbital (1s) is not filled, the electric field of the nucleus will pull an electron out of the vacuum, resulting in the spontaneous emission of a positron.[163] This does not happen if the innermost orbital is filled, so that element 173 is not necessarily the end of the periodic table.[160]

text: Optimal form

text: The many different forms of periodic table have prompted the question of whether there is an optimal or definitive form of periodic table.[164] The answer to this question is thought to depend on whether the chemical periodicity seen to occur among the elements has an underlying truth, effectively hard-wired into the universe, or if any such periodicity is instead the product of subjective human interpretation, contingent upon the circumstances, beliefs and predilections of human observers. An objective basis for chemical periodicity would settle the questions about the location of hydrogen and helium, and the composition of group 3. Such an underlying truth, if it exists, is thought to have not yet been discovered. In its absence, the many different forms of periodic table can be regarded as variations on the theme of chemical periodicity, each of which explores and emphasizes different aspects, properties, perspectives and relationships of and among the elements.[n 18]