document_title: Quantum Leap

question_text: what was the final episode of quantum leap

text: Quantum Leap

text: Premise[edit]

text:
"Theorizing that one could time travel within his own lifetime, Doctor Sam Beckett led an elite group of scientists into the desert to develop a top secret project, known as "Quantum Leap". Pressured to prove his theories or lose funding, Doctor Beckett prematurely stepped into the Project Accelerator and vanished. He awoke to find himself in the past, suffering from partial amnesia and facing a mirror image that was not his own. Fortunately, contact with his own time was maintained through brainwave transmissions with Al, the Project Observer, who appeared in the form of a hologram that only Doctor Beckett could see and hear. Trapped in the past, Doctor Beckett finds himself leaping from life to life, putting things right that once went wrong and hoping each time that his next leap will be the leap home."

- Opening narration by Deborah Pratt, season two, episodes 13–22.

tag: div

text: Quantum Leap follows the narrative of Dr. Sam Beckett (Bakula), a physicist who has become stuck in the past as a result of a time-travel experiment gone wrong, and his attempts to return to his present, the late 20th century, by altering events in the past for the better, with the aid of a hologram of his friend Admiral Al Calavicci (Stockwell), monitoring him from Sam's present.[2][3]

text: In the series premiere, Sam has theorized the ability to travel in one's own lifetime and is the lead of the government-funded Project Quantum Leap, operating from a secret laboratory in New Mexico; Al oversees the project for the government. When Al learns that funding for the project is in danger of being pulled because no demonstrable results have come from the project, Sam takes it upon himself to step into the Quantum Leap accelerator to prove the project works and is sent into the past. When Sam gains consciousness, he finds himself suffering from partial amnesia, and is more surprised to find that his appearance to others, including what he sees in the mirror, is not his own face. He finds that Al has come to his aid as a hologram that only Sam can see and hear, as it is tuned to his brainwaves. Al, working with the project's artificial intelligence Ziggy (voiced by Deborah Pratt), determines that Sam must alter an event in the current period he is in so as to re-engage the Quantum Leap process and return home. Al helps Sam overcome some facets of his "Swiss-cheese memory" and provides information on history as it originally happened. He also updates Sam on future events and relates possible outcome probabilities using a handheld communication device in contact with Ziggy. The device is often temperamental and must be struck a few times as it emits electronic beeping and whirring sounds before the information is revealed. With Al and Ziggy's help, Sam is able to successfully change history, and then leaps out, only to find himself in the life of someone else in a different period of time.[4]

text: Episodes in the series subsequently follow Sam's reaction to each leap (typically ending the cold open with him uttering "Oh, boy!" on discovering his situation), and then working with Al and Ziggy to figure out his new identity and whom he needs to help to "set right what once went wrong" and trigger the next leap.[5] An episode typically ends as a cliffhanger showing the first few moments of Sam's next leap (along with him again uttering "Oh, boy!" on discovering his situation), which is repeated in the following episode's cold open. Though initially Sam's leaping is believed by Al and the others on the Quantum Leap team to be random, the characters come to believe in later seasons that someone or something is controlling Sam's leaping, and this is a central focus of the show's finale episode, "Mirror Image".

text: When Sam leaps, his body is physically present in the past, although he appears to others as the person into whom he leaped. In one case, after leaping into a Vietnam veteran who has lost both legs, Sam is still able to walk normally, but appears to others as if he is floating. Sam's body and mind may become jumbled with those into whom he has leaped. In one situation, he leaps into a woman near the end of her pregnancy and feels her birth pains, while in another episode, he leaps into the body of Lee Harvey Oswald and feels an intense pressure to assassinate John F. Kennedy, despite knowing that it is the wrong thing to do. Similarly, the persons into whom Sam has leaped are brought into the future, where they appear as Sam to the others; they are normally kept in an isolated waiting room to prevent them from learning anything about the future, and they return to their own time when Sam leaps.

text: In most of Sam's leaps, the changes he makes are small on the grand scale, such as saving the life of a person who might otherwise have died, or helping making someone's life better. Selected episodes, however, demonstrate more dramatic effects of his time travels. In one episode, Sam's actions ultimately lead to Al's death prior to the project, and Sam finds himself suddenly aided by a new hologram, "Edward St. John V" (played by Roddy McDowall), and must work to prevent Al's death. In another episode, when again the project's funding is threatened, Sam helps a young woman successfully pass the bar; this results in her becoming one of the members of Congress who oversees the project and aids in the restoration of its funding. In the episode involving Lee Harvey Oswald, while Sam and Al do not prevent the assassination of Kennedy, Sam's actions prevent Oswald from making a second shot that killed Jacqueline Kennedy in the original fictional history.

text: Because of the time-travel aspect, many episodes allude to famous people or incidents indirectly, such as Sam suggesting to young Donald Trump that New York real estate will be valuable in the future, suggesting the lyrics of "Peggy Sue" to a teenaged Buddy Holly, showing young Michael Jackson his signature moonwalk dance for the first time, giving Dr. Henry Heimlich the idea for his namesake maneuver by saving him from choking,[3] and setting in place actions that lead to the discovery of the Watergate scandal. Two notable episodes place Sam directly at the center of significant historical events, one being the leap into Oswald. In "Goodbye Norma Jean", Sam appears as Marilyn Monroe's bodyguard, who saves her life and convinces Marilyn to remain alive for her starring role in The Misfits. Other episodes explore the past of the main characters, such as Sam saving his brother from being killed in the Vietnam War, and saving Al's marriage to Beth.

text: In the final episode, "Mirror Image", Sam leaps through spacetime as himself (without replacing another person), arriving at the exact time of his birth, where he meets a mysterious barkeep (Bruce McGill, who also appeared in the first episode in a different role). The barkeep is aware of Sam's situation and assures him that Sam himself controls the very nature and destinations of his leaps ("to make the world a better place"), and that Sam is always able to return home at any time he truly wants. In the final episode's epilogue, Sam is shown to leap back to visit Al's wife Beth as himself again, assuring her that her husband (who was a prisoner of war at the time) will return home to her; this results in Al and Beth remaining happily married in the future,[3] while Sam continues leaping, never returning home.

text: Cast and characters[edit]

text:
Dr. Samuel "Sam" Beckett (played by Scott Bakula) is a quantum physicist with six doctoral degrees. He grew up on his parents' farm in Elk Ridge, Indiana, with an older brother (Tom) and a younger sister (Katie). Sam's idol is Albert Einstein.
Albert "Al" Calavicci, USN (played by Dean Stockwell) is a womanizing U.S. Navy rear admiral and Sam's best friend, who grew up in an orphanage and was later active in the Civil Rights Movement. At the time of Sam's leaps, Al spends his free time with his lover and the project's medical technician Tina Martinez (played by Gigi Rice), who appears in the fourth-season episode "The Leap Back".
Ziggy (voiced by the narrator and co-executive producer Deborah Pratt) is the self-aware artificial intelligence "parallel hybrid computer with an ego" that runs the Project Quantum Leap, and helps Sam throughout his leaps; appearing in the fourth-season episode "The Leap Back".
Irving "Gooshie" Gushman (played by Dennis Wolfberg) is the project's often-mentioned head programmer, who is said to have bad breath. He appears in five episodes, including the finale.
Dr. Verbena Beeks (played by Candy Ann Brown) is often mentioned as the project's psychiatrist. She appears in two episodes throughout the series.

text: In each episode, a different cast of guest characters appears, mostly the ones whom Sam replaces with his leaps. Several other characters are referred to regularly throughout the series, but are mostly unseen.

text: Production[edit]

text: Development[edit]

text: The main premise for Quantum Leap was inspired by such movies as Heaven Can Wait and Here Comes Mr. Jordan.[citation needed] Series creator Donald P. Bellisario[3][6] saw its concept as a way of developing an original anthology series, as anthologies were unpopular with the networks.[3]

text: The series ran on NBC[7] for five seasons, from March 1989 through May 1993.

text: Soundtrack[edit]

text: The theme for the series was written by Mike Post.[3] It was later rearranged for the fifth season, except for the series finale episode, which featured the original theme music. Scores for the episodes were composed by Post and Velton Ray Bunch.

text: A soundtrack album was first released in 1993, titled "Music from the Television Series Quantum Leap", dedicated to John Anderson, who played Pat Knight in "The Last Gunfighter". It was released by GNP Crescendo on CD and cassette tape.

text:
No.
Track[8]
Composer(s)
Length
Episode

1
Prologue (Saga Sell)
Mike Post, Velton Ray Bunch
Deborah Pratt (voice over)
1:05

2
Quantum Leap (Main Title)
Mike Post
1:15

3
Somewhere in the Night
Scott Bakula
3:32
Piano Man

4
Suite from the Leap Home
Velton Ray Bunch
3:37
The Leap Home, part 1

5
Imagine
John Lennon
3:05
The Leap Home, Part 1

6
Sam's Prayer
Velton Ray Bunch
1:52
A Single Drop of Rain

7
Blue Moon of Kentucky
Bill Monroe
1:41
Memphis Melody

8
Baby, Let's Play House
Arthur Gunter
2:13
Memphis Melody

9
Shoot Out
Velton Ray Bunch
3:03
The Last Gunfighter

10
Medley from Man of La Mancha
Scott Bakula
6:18
Catch a Falling Star

11
Bite Me
Velton Ray Bunch
3:29
Blood Moon

12
Alphabet Rap
Dean Stockwell
2:05
Shock Theater

13
Suite from "Lee Harvey Oswald"
Velton Ray Bunch
14:55
Leaping on a String

14
Fate's Wide Wheel
Scott Bakula
3:05
Glitter Rock

15
A Conversation with Scott Bakula
Scott Bakula (interview)
12:02

16
Quantum Leap (Prologue and Main Title Reprise)
Mike Post, Velton Ray Bunch
2:20

text: Episodes[edit]

text: Broadcast history[edit]

text: The Quantum Leap series was initially moved from Friday nights to Wednesdays. It was later moved twice away from Wednesdays to Fridays in late 1990, and to Tuesdays in late 1992. The series finale aired in its Wednesday slot in May 1993.[3]

text: The most frequent time-slot for the series is indicated by italics:

text:
Sunday at 9:00–11:00 PM on NBC: March 26, 1989
Friday at 9:00–10:00 PM on NBC: March 31, 1989 – April 21, 1989
Wednesday at 10:00–11:00 PM on NBC: May 3—17, 1989; September 20, 1989 – May 9, 1990; March 6, 1991 – May 20, 1992
Friday at 8:00–9:00 PM on NBC: September 28, 1990 – January 4, 1991
Tuesday at 8:00–9:00 PM on NBC: September 22, 1992 – April 20, 1993
Wednesday at 9:00–10:00 PM on NBC: May 4, 1993

text: In the United Kingdom, the show began on BBC Two on February 13th, 1990[1], airing Tuesday evenings at 9:00PM. The final episode was scheduled to be aired on June 14th, 1994, but altered schedules after the death of British dramatist Dennis Potter earlier that month delayed the airing until June 21st, 1994.[2]. Repeat episodes continued on the channel at various times until December 28th, 1999[3]. It has since aired several times on satellite and cable television, rerunning late at night on television channel Cozi TV.

text: On 16 June 2016, Scott Bakula made a brief reprise of his role as Sam Beckett on The Late Show with Stephen Colbert. Stephen Colbert makes reference to an episode where Sam Beckett has leapt into the body of a 1950s New York cab driver, whose comment about investing in New York real estate is heard by a young Donald Trump. Using a handset to talk to Ziggy, Stephen Colbert leaps back as a hologram to help Sam Beckett attempt to change the future.[9]

text: Home media[edit]

text: Universal Studios Home Entertainment has released the entire, digitally remastered, Quantum Leap series on DVD:[10][11]

text: On April 13, 2016, it was announced that Mill Creek Entertainment had acquired the rights to the series and re-released the first two seasons on DVD on June 7, 2016.[12]

text: On February 7, 2017, Mill Creek re-released Quantum Leap- The Complete series on DVD and also released the complete series on Blu-ray for the very first time.[13] The 18-disc set contains all 97 episodes of the series as well as most of the original music.

text:
Season - DVD name
Episodes
DVD release date

Region 1
Region 2
Region 4

Season 1 - The Complete First Season
9
June 8, 2004
November 8, 2004
May 2, 2005

Season 2 - The Complete Second Season
22
December 14, 2004
October 31, 2005
February 7, 2006

Season 3 - The Complete Third Season
22
May 10, 2005
December 12, 2005
June 7, 2006

Season 4 - The Complete Fourth Season
22
March 28, 2006
June 26, 2006
November 2006

Season 5 - The Complete Fifth Season
22
November 14, 2006
December 26, 2006
February 21, 2007

Seasons 1–5 - The Complete Series
(The Complete Collection)
97
November 4, 2014[10]
October 8, 2007[11]
N/A

text: Reception[edit]

text: Despite its struggling start with poor broadcast timings,[3] the series had gained a large 18–49 demographics of viewers.[citation needed] The finale was viewed by 13 million American households.[14] In 2004 and 2007, Quantum Leap was ranked #15 and #19 on TV Guide's "Top Cult Shows Ever."[1]

text: Awards[edit]

text: Along with 43 nominations, Quantum Leap received 17 awards (listed below).[15][16]

text:
Year
Award
Category
Winner(s)
Episode

1989
Primetime Emmy Award
Outstanding Cinematography for a Series
Roy H. Wagner
Genesis, Part 1

Outstanding Achievement in Hairstyling for a Series
Virginia Kearns
Double Identity

1990
Quality TV Award
Best Actor in a Quality Drama Series
Scott Bakula

Golden Globe Award
Best Performance by an Actor in a Supporting Role in a Series,
Mini-Series or Motion Picture Made for TV
Dean Stockwell

Primetime Emmy Award
Outstanding Cinematography for a Series
Michael W. Watkins
Pool Hall Blues

1991
Quality TV Award
Best Actor in a Quality Drama Series
Scott Bakula

Best Supporting Actor in a Quality Drama Series
Dean Stockwell

Edgar Award
Best Television Episode
Paul Brown
Good Night, Dear Heart

DGA Award
Outstanding Directorial Achievement in Dramatic Series' - Night
Michael Zinberg
The Leap Home, Part 2 - Vietnam

Primetime Emmy Award
Outstanding Achievement in Makeup for a Series
Gerald Quist
Michael Mills
Jeremy Swan
The Leap Home, Part 1

Outstanding Cinematography for a Series
Michael W. Watkins
The Leap Home, Part 2 - Vietnam

1992
Quality TV Award
Best Actor in a Quality Drama Series
Scott Bakula

Golden Globe Award
Best Performance by an Actor in a TV-Series - Drama
Scott Bakula

1993
Quality TV Award
Best Actor in a Quality Drama Series
Scott Bakula

Young Artist Award
Best Young Actress Guest-Starring in a Television Series
Kimberly Cullum

ACE Award
Best Edited One Hour Series for Television
Jon Koslowsky
A Song for the Soul

Primetime Emmy Award
Outstanding Individual Achievement in Editing for a Series,
Single Camera Production
Jon Koslowsky
Lee Harvey Oswald

text: Other media[edit]

text: Books[edit]

text:
Barrett, Julie, The A–Z of Quantum Leap. Boxtree Ltd., London 1995. ISBN 0-7522-0628-1
Chunovic, Louis, Quantum Leap Book. Boxtree Ltd., London 1993. ISBN 1-85283-866-3
Schuster, Hal, The Making of Quantum Leap. HarperCollins, London 1996. ISBN 0-06-105438-0

text:
Robitaille, Julie, The Ghost and the Gumshoe. Corgi, London 1990. ISBN 1-85283-397-1. Re-published in U.K. by Boxtree Ltd., London 1994. (Novelization of "Play It Again, Seymour" and "A Portrait of Troian")
McConnell, Ashley, Quantum Leap: The Novel. Ace Books, 1992. ISBN 0-441-69322-9. Re-published in the UK as Carny Knowledge. Boxtree Limited, London 1993. ISBN 1-85283-871-X
McConnell, Ashley, Too Close for Comfort. Ace Books, 1993. ISBN 0-441-69323-7.
Robitaille, Julie, The Beginning. Boxtree Ltd., London 1994. ISBN 1-85283-392-0. (Novelization of the pilot episode)
McConnell, Ashley, The Wall. Ace Books, 1994. ISBN 0-441-00015-0.
McConnell, Ashley, Prelude. Ace Books, 1994. ISBN 0-441-00076-2.
Melanie Rawn: Knights of the Morningstar. Ace Books, 1994. ISBN 0-441-00092-4.
Melissa Crandall: Search and Rescue. Ace Books, 1994. ISBN 0-441-00122-X.
McConnell, Ashley, Random Measures. Ace Books, 1995. ISBN 0-441-00182-3.
Storm, L. Elizabeth, Pulitzer. Ace Books, 1995. ISBN 1-57297-022-7.
Henderson, C.J. and Laura Anne Gilman, Double or Nothing. Ace Books, 1995. ISBN 1-57297-055-3.
Walton, Barbara E., Odyssey. Boulevard, 1996. ISBN 1-57297-092-8.
Peel, John, Independence. Boulevard, 1996. ISBN 1-57297-150-9. Re-published in the U.K. as Leap into the Unknown. Boxtree Ltd., London 1996 ISBN 0-7522-0137-9.
Storm, L. Elizabeth, Angels Unaware. Boulevard, 1997. ISBN 1-57297-206-8.
Davis, Carol, Obsessions. Boulevard, 1997. ISBN 1-57297-241-6.
Schofield, Sandy (Dean Wesley Smith and Kristine Kathryn Rusch), Loch Ness Leap. Boulevard, 1997 ISBN 1-57297-231-9.
Kent, Melanie, Heat Wave. Boulevard, 1997 ISBN 1-57297-312-9.
DeFilippis, Christopher, Foreknowledge. Boulevard, 1998 ISBN 0-425-16487-X .
Peterman, MindySong And Dance. Boulevard, 1998 ISBN 0-425-16577-9.
Davis, Carol, and Esther D. Reese: Mirror's Edge. Boulevard, 2000 ISBN 0-425-17351-8.

text: Comics[edit]

text: Innovation Publishing produced a series of comic books which ran for thirteen issues from September 1991 through August 1993. As with the television series, each issue ended with a teaser preview of the following issue and Sam's exclamation of "Oh, boy." Among the people Sam found himself leaping into in this series were:[17]

text:
Issue
Title
Person
Date

1
"First There Was a Mountain, Then There Was No Mountain, Then There Was"
High school teacher named Karen Connors in Memphis, Tennessee.
March 25, 1968

2
"Freedom of the Press"
Death row inmate named Willie Jackson, who must prevent a murder on the outside.
June 11, 1962

3A
"He Knows If You've Been Bad or Good..."
Part-time Santa Claus, who goes by the name of Nick.
December 20, 1963

3B
"The Infinite Corridor"
Student at MIT named Matt Randall, who is researching quantum physics.
April 2, 1968

4
"The 50,000 Quest"
Contestant amid the quiz show scandals.
August 15, 1958

5
"Seeing is Believing"
Newspaper reporter/columnist, who responds to a girl seeing a UFO.
November 14, 1957

6
"A Tale of Two Cindys"
Teenage girl with an identical twin sister.
February 12, 1959

7A
"Lives on the Fringe"
Professional golfer with mafia after him.
1974

7B
"Sarah's Got a Gun"
Bus driver, who discovers child abuse.
May 19, 1953

8
"Getaway"
Bank robber, while the leapee tours the Project with Al.
1958

9
"Up Against a Stonewall"
Sequel to "Good Night, Dear Heart." Stephanie Heywood is released from prison after serving twelve years for manslaughter.
June 22, 1969

10
"Too Funny For Words"
Stand-up comedian, who befriends a fading silent movie star.
June 13, 1966

11
"For the Good of the Nation"
Doctor studying the effects of LSD on human subjects.
July 1958

12
"Waiting"
Gas station attendant with a lot of time on his hands.
April 24, 1958

13
"One Giant Leap"
An extraterrestrial aboard an orbiting spaceship.
June 5, 1963

text: Few of the comic stories referenced episodes of the television series, with the exception of the ninth issue, "Up Against a Stonewall."

text: Possible continuation[edit]

text: There have been occasional announcements of plans to revisit or restart the series. In July 2002, the Sci-Fi Channel announced its development of a two-hour television film based on Quantum Leap, which it was airing in reruns at the time, that would have served as a backdoor pilot for a possible new series, with Bellisario as executive producer.[18] During the TV Guide panel at the 2010 San Diego Comic-Con International, Scott Bakula said that Bellisario was working on a script for a projected Quantum Leap feature film.[19] In October 2017, Bellisario confirmed at the L.A. Comic Con that he has finished a script for a feature film.[20]


document_title: LA Devotee

question_text: panic at the disco la devotee video cast

root

text: LA Devotee

text: Background[edit]

text: "LA Devotee" was written by Panic! at the Disco (A.K.A Brendon Urie) throughout 2015. The song's inspiration derives from Urie's passion for Los Angeles and is about someone who has fallen in love with L.A. and will stop at nothing to survive and succeed in the city.[4] A video of the audio for "LA Devotee" was uploaded to Fueled by Ramen's official YouTube channel on the day of its release, November 26, 2015.[5] It has been streamed over 27 million times on YouTube and over 80 million times on Spotify as of February 2018.

tag: p

text: Music video[edit]

text: The song's official music video was released September 22, 2016, starring Noah Schnapp, an actor who is known for his role in the Netflix series Stranger Things. The video starts with a young girl nervously trying to cross a field with a dog barking in the background. The girl falls down and gets kidnapped by an unknown cloaked figure as the camera shows a shot of the mysterious "Join Us" logo cropped into the field. The next scene shows a young boy being strapped to a chair singing the song while experiencing bizarre things, with Brendon also singing the song on a screen. The young girl also makes an appearance forcing the boy to drink something. The last scene shows four cloaked figures strapping two mechanisms to the boy, causing him to be electrocuted and then suffer a seizure. Afterwards, the video ends with Brendon walking up to him with rubber gloves in a menacing manner. It is unknown what Brendon is to do next. On "The Death of a Bachelor Tour" before "This Is Gospel" A video is shown, showing Urie's involvement and origins with the cloaked figures, showing Urie being brutally tortured.

text: Between shots of Noah being tortured we can see several disturbing images, including men dressed having animal heads, blood poured over a skull, children with black holes for their eyes, and a symbol of the Church of Satan (featuring a Baphomet's head inside an inverted pentagon) projected over Urie's face.

text: Charts[edit]

text:
Chart (2015)
Peak
position

US Hot Rock Songs (Billboard)[6]
15

tag: table

text: Certifications[edit]

text:
Region
Certification
Certified units/Sales

United States (RIAA)[7]
Gold
500,000

*sales figures based on certification alone
^shipments figures based on certification alone
sales+streaming figures based on certification alone


document_title: Tam-Tams

question_text: what time do tam tams start in montreal

question_tokens: what time do tam tams start in montreal

text: Tam-Tams

text: Events[edit]

text: Thousands of drum players, dancers, vendors and visitors come together every Sunday afternoon throughout the temperate months, occupying much of the open space on the eastern edge of Mount Royal Park (also known as Fletcher's Field). Jeanne-Mance Park, located directly across Avenue du Parc from where the Tam-Tams take place, serves as the city's main outdoor sporting ground. As such, the entire area is generally quite popular on Sundays in the summertime, drawing an exceptionally diverse crowd to myriad activities. The Tam-Tams typically start around 10:30am and continue until sunset. It is not an officially sanctioned nor sponsored event, simply a regular if technically spontaneous event. As such, it's difficult to pinpoint when it started or what motivated the first drum circle.

text: History[edit]

text: Spending Sundays in Mount Royal Park has been popular since the park was inaugurated in 1876, and the nature and design of Fletcher's Field has always made it a popular spot for picnics and sunbathers. Musical performances have been a staple since time immemorial, as brass bands, military and marching bands were popular entertainment until around the time of the Second World War. Moreover, the location of the Tam-Tams isn't too far from where Montreal's first permanent exposition hall, the Crystal Palace, was located. As such the location of the Tam-Tams is well rooted in the history of Montreal public life and festivities.

text: Anecdotal evidence suggests the first people to begin regular drumming at the base of the Cartier monument back in the mid-1960s. A group of students from the West Indies who lived in the area arranged to meet at the monument and practice in a public place to avoid disturbing their neighbours.

text: However, alternate anecdotal evidence suggests more recent beginnings. Quoted from an Ottawa-based musician and educator: "...1992, it started with four ceremonial guard guys (me included) meeting up to buy pot from some guys we met at Steve's music store. They were buying djembes and we had just attended a clinic with Memo Ascevedo, and bought traditional go-go bells, tambime (not tambourine), clave, talking drum, etc. He had a Cuban buddy who played bongos, and we met at the statue to exchange rhythmic ideas. We shared an apartment on l'esplanade with 6 other army guys, all drummers. 3 of us were on leave at alternate times, 6 days of work, 3 days off. So there was always someone at the house. We agreed to meet every Sunday at the park, get high, and jam. Other guys started coming, it watered down the quality of the jam, but it got bigger and bigger..."

text: But it would be many years before the Tam-Tams became an element of the Montreal counter-culture scene. In this respect, anecdotal evidence suggests the Tam-Tams' origins date back to Saint Jean Baptiste Day 1976 when the City of Montreal located festivities related to the day entirely within the 'mountain domain'. In this case the mountain became a playground for the city's youth and counter-culture, with music throughout the day and many bonfires throughout the night. Damage to the park was so extreme the city would never again use the mountain for large-scale organized festivities.

text: Present day[edit]

text: Today's Tam-Tams are still centred on the drum circle, but have evolved to also include artisanal vendors, DJs, performance artists, exhibitionists and a battle-royal for fantasy role players.

text: Because of the 'laissez-faire' attitude that characterizes the festivities, drug dealing, drug use and public drinking are tolerated to a degree. The Tam-Tams is strongly associated with cannabis culture, and though Montreal police are generally present they tend to disregard consumption of alcohol and cannabis. The general rule observed by Montrealers and respected by the police is discretion, moderation and not consuming in view of children.


document_title: Train of thought

question_text: where does the phrase train of thought come from

text: Train of thought

text: This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (April 2014) (Learn how and when to remove this template message)

text: The train of thought or track of thought refers to the interconnection in the sequence of ideas expressed during a connected discourse or thought, as well as the sequence itself, especially in discussion how this sequence leads from one idea to another.

text: When a reader or listener "loses the train of thought" (i.e., loses the relation between consecutive sentences or phrases, or the relation between non-verbal concepts in an argument or presentation), comprehension is lost of the expressed or unexpressed thought.[1]

text: The term "train of thoughts" was introduced and elaborated as early as in 1651 by Thomas Hobbes in his Leviathan, though with a somewhat different meaning (similar to the meaning used by the British associationists):

text:
By Consequence, or train of thoughts, I understand that succession of one thought to another which is called, to distinguish it from discourse in words, mental discourse.
When a man thinketh on anything whatsoever, his next thought after is not altogether so casual as it seems to be. Not every thought to every thought succeeds indifferently.


document_title: Oppo

question_text: oppo is sponsor of which country's national cricket team

question_tokens: oppo is sponsor of which country 's national cricket team

text: Oppo

text: History[edit]

text: The brand name Oppo was registered in China in 2001 and launched in 2004.[2] Since then, they have expanded to all parts of the world.

text: In June 2016, Oppo became the biggest smartphone maker in China,[3] selling its phones at more than 200,000 retail outlets.[4]

text: In 2017, Oppo successfully won the bid to sponsor the Indian national cricket team and has achieved the rights to display their logo on the team’s kits from 2017 to 2022. Between this period the Indian national cricket team will play 259 International matches consisting of 62 Tests, 152 ODIs and 45 T20 Internationals. This number also includes the 2019 World Cup in England and 2020 T20 World Cup in Australia. The current base price for bilateral matches involving India has been set at Rs 4.1 crore (approx.) and for Asian Cricket Council (ACC) and International Cricket Council (ICC) matches, it is Rs 1.56 crore (approx.) - almost a four-fold increase from its earlier rate.

text: Controversies[edit]

text: In 2017 the company first saw protest over India's national flag insult row.[5] It was followed by a mass resignation of the Punjab service unit.[6]

text: Promoters[edit]

text: Korean boy band 2PM prepared a song known as "Follow Your Soul" in a promotional deal with Oppo for launching its brand in Thailand in 2010.[7] In June 2015, the company signed an agreement with FC Barcelona to become an official partner of the Catalan football club.[8][9][10]

text: Also in 2015, Oppo hired Yang Mi and Luhan as the product ambassador in China,[11] followed by Sarah Geronimo and Alden Richards, who was named as the first brand ambassador of Oppo in the Philippines.[12]

text: Oppo India hired actors Hrithik Roshan and Sonam Kapoor as their brand ambassadors. The cricketer Yuvraj Singh too has been featured in some of their advertisements. Oppo India has recently launched a campaign starring Bollywood couple Bipasha Basu and Karan Singh Grover for Oppo F1s Rose Gold edition.

text: Oppo Indonesia hired Isyana Sarasvati, Raisa Andriana, Reza Rahadian and Chelsea Islan as their brand ambassadors.

text: In 2016, PBA tied up with this company as its official smartphone partner starting from 2016 PBA Commissioner's Cup which was held on February 10.

text: Oppo also hires celebrity endorsers in Vietnam, especially Son Tung M-TP who endorses three smartphone units like Neo 5, Neo 7 and F1s. Oppo made a sponsorship to one of Vietnam's top-rated reality shows, The Face Vietnam.

text: In October 2017, Oppo Thailand launched a new ad of Oppo F5 smart phone with a new ad presenter: famous Thai actor, Nadech Kugimiya. Oppo Malaysia also launched a new Oppo F5 smartphone with Fattah Amin and Ayda Jebat as their brand ambassadors.

text: Products[edit]

text: Phones[edit]

text: Oppo has produced a numerous different phones some of their most notable phones are listed below.

text: Find 5[edit]

text: The OPPO Find 5 was released in America in February 2013, the OPPO Find 5 featured clean lines, a thin rectangular shape, and an overall elegant appearance.[13] The OPPO Find 5 had a pixel density of 441 ppi, which puts it in the highest range of the mobile phones with HD display at its release time. In July 2013, a refreshed OPPO Find 5 launched in China. The processor has been changed to Snapdragon 600 instead of the Snapdragon S4 Pro. The Android version was updated to Android 4.2.2 as well while other specifications remained the same.[14]

text: Find 7[edit]

text: The OPPO Find 7 is a phablet with 3GB of RAM and a 2.5 GHz Quad-Core processor.[15] The OPPO Find 7 is also available in another variant called the Find 7a, which has a 1080p screen and 2GB of RAM compared to the Find 7, which sports higher specs. It was announced on 19 March 2014 and was released in April 2014. It is similar in design to the OnePlus One released in April 2014.

text: On 23 September 2013, OPPO announced the N1, which has a 5.9″ 1080p display (373 ppi), 1.7 GHz Qualcomm Snapdragon 600 processor, 3,610mAh battery, 16GB or 32GB of storage, 2GB RAM, and a 13MP camera that can rotate, touch-panel on the back, and option to flash CyanogenMod.[16] It was released in December 2013.

text: A successor, the OPPO N3, is priced at $449 as of early 2016.[17]

text: Maintaining the reputation of launching newer mobile phones at a regular interval, Oppo introduced the Oppo A71 in India at an introductory price of Rs.12,490. The phone sported a 5.2 Inch display with 3GB RAM and Octa Core processor with latest the Android 7.1 Nougat.

text: In May 2017, OPPO launched the A77 in Taiwan. It is fueled by a 1.5 GHz octa-core MediaTek MT6750T processor combined with 4GB of RAM and runs on Android 6.0 Marshmallow OS.[18]

text: The OPPO R5, which was launched in November 2014, was at the time the world's thinnest smartphone.[19] It is 4.85mm in thickness except for a slight bulge where the camera lens is located. The R5 has a 2,000 mAh battery which can be charged up to 75% in 30 minutes using OPPO's own VOOC Flash Charging technology.[20] The R5 uses a SnapDragon 615 octa-core processor, running at 2.1 GHz.[17][21] OPPO began shipping the R5 in the UK on 20 February 2015.[22] One of OPPO's older phones, the Finder, previously held the record for the world's thinnest smartphone.[23]

text: On 3 August 2016, Oppo launched the F1s in India.[citation needed] The Oppo F1s is a selfie-centric phone which succeeds the Oppo F1. The F1s sports a 13 MP primary camera at the back and has a 16 MP secondary camera on the front. There is a fingerprint scanner housed on the home button which can not only be used to unlock the phone, but, open apps as well. The Oppo F1s is powered by MediaTek's MT6750 octa-core processor which is coupled with 3 GB RAM and Mali-T860 MP2 GPU. It runs on ColorOS 3.0 based on Android 5.1 Lollipop and features a 5.5-inch HD IPS display which is backed by 3075 mAh battery.

text:
Finder
Find 5[24]
U705T Ulike 2
U701 Ulike
R610
R811 Real
R817 Real
R819 / R819T
T29
N1
Find 7a
Find 7
R5
N3
R7
R7 Plus
R7 Lite
R7s
F1
F1s
Joy Plus/R1011
showR9

Dimensions
125 × 66 × 6.65 mm
141.8 × 68.8 × 8.8 mm
127 × 63.7 × 9 mm
123 × 64 × 9.7 mm
112.8 × 55.5 × 14.3 mm
115.2 × 61.5 × 10.9 mm
123 × 63 × 9.7 mm
136.5 × 68 × 7.3 mm
131.5 × 67 × 10.5 mm
170.7 × 82.6 × 9 mm
152.6 × 75 × 9.2 mm
152.6 × 75 × 9.2 mm
148.9 × 74.5 × 4.9 mm
161.2 × 77 × 9.9 mm
143 × 71 × 6.3 mm
158 × 82 × 7.75 mm
143 × 71 × 6.3 mm
151.8 × 75.4 × 7 mm
143.5 × 71 × 7.3 mm
154.5 x 76 x 7.38 mm
124 x 63 x 9.9 mm
151.8 x 74.3 x 6.6 mm

Weight
125 g
165 g
113 g
130 g
102.5 g
119 g
125 g
110 g
160 g
213 g
170 g
171 g
155 g
192 g
147 g
192 g
147 g
155 g
134 g
160 g
125 g
145 g

Display
Super AMOLED Plus
IPS LCD capacitive
TFT capacitive
IPS LCD capacitive
IPS LCD capacitive
TFT capacitive
IPS LCD capacitive
IPS LCD capacitive
TFT capacitive
TFT capacitive
IPS LCD capacitive
IPS LCD capacitive
AMOLED
TFT capacitive
AMOLED
AMOLED
AMOLED
AMOLED
IPS LCD capacitive
IPS LCD capacitive
IPS LCD capacitive
AMOLED

Resolution
800x480
1920x1080
960x540
800x480
480x320
480x320
800x480
1280x720 pixels
960x540
1920x1080
1920x1080
2560x1440
1920x1080
1920x1080
1920x1080
1920x1080
1280x720
1920x1080
1280x720
1280x720
480x800
1920x1080

Internal Storage
16 GB
16/32 GB
16 GB
4 GB
4 GB
4 GB
4 GB
16 GB
4 GB
16/32 GB
16/32 GB
16/32 GB
16 GB
32 GB
16 GB
32 GB
16 GB
32 GB
16 GB
32 GB
4 GB
64 GB

Memory
1 GB
2 GB
1 GB
512 MB
512 MB
512 MB
1 GB
1 GB
1 GB
2 GB
2 GB
3 GB
2 GB
2 GB
3 GB
3 GB
2 GB
4 GB
3 GB
3 GB
4 GB
4 GB

Rear Camera
8 MP
13 MP
8 MP
5 MP
3 MP
3 MP
8 MP
8 MP
8 MP
13 MP
13 MP
13 MP
13 MP
16 MP
13 MP
13 MP
16 MP
13 MP
13 MP
13 MP
3 MP
16 MP

Front Camera
1.3 MP
1.9 MP
5 MP
2 MP
None
Yes
0.3 MP
1.9 MP
0.3 MP
Same as back, uses rotating module
5 MP
5 MP
5 MP
Same as back, uses rotating module
8 MP
8 MP
8 MP
8 MP
8 MP
16 MP
2 MP
13 MP

Battery
Li-Ion 1500 mAh
Li-Ion 2500 mAh
Li-Ion 2020 mAh
Li-Ion 1710 mAh
Li-Ion 1100 mAh
Li-Ion 1520 mAh
Li-Ion 1710 mAh
Li-Ion 2000 mAh
Li-Ion 3150 mAh
Li-Ion 3610 mAh VOOC[25]
Li-Po 2800 mAh VOOC
Li-Po 3000 mAh VOOC
Li-Po 2000 mAh VOOC
Li-Po 3000 mAh VOOC
Li-Po 2320 mAh VOOC
Li-Po 4100 mAh VOOC
Li-Po 2320 mAh
Li-Po 3070 mAh VOOC
Li-Po 2500 mAh
Li-Po 3075 mAh
Removable Li-Ion 1700 mAh
VOOC

Non-Removable Li-Po 2850 mAh

Processor
Dual-core 1.5 GHz
Quad-core 1.5 GHz
Quad-core 1 GHz
Dual-core 1 GHz
Dual-core 1 GHz
Dual-core 1 GHz
Dual-core 1 GHz
Quad-core 1.2 GHz
Dual-core 1 GHz
Quad-core 1.7 GHz
Quad-core 2.3 GHz
Quad-core 2.5 GHz
Octa-core 1.5 GHz
Quad-core 2.3 GHz
Octa-core 1.5 GHz
Octa-core 1.5 GHz
Octa-core 1.5 GHz
Octa-core 1.5 GHz
Octa-core 1.7 GHz
Octa-core 1.5 GHz
Dual-Core 1.3 GHz Cortex-A7
Octa-core, 2.0 GHz, ARM Cortex-A53

OS
4.0.4 Ice Cream Sandwich
ColorOS, based on Android 4.2.2
4.0.4 Ice Cream Sandwich
4.0.4 Ice Cream Sandwich
4.0.4 Ice Cream Sandwich
4.0.4 Ice Cream Sandwich
4.0.4 Ice Cream Sandwich
4.2.1 Jelly Bean
4.0.4 Ice Cream Sandwich
ColorOS, based on Android 4.2
ColorOS, based on Android 4.3
ColorOS, based on Android 4.3
ColorOS 2.0, based on Android 4.4
ColorOS 2.0, based on Android 4.4
ColorOS 2.1, based on Android 4.4
ColorOS 2.1, Android 7.1
ColorOS 2.1, Android 5.1
ColorOS 2.1, Android 5.1
ColorOS 2.1, Android 5.1
ColorOS 3.0, Android 5.1
Android OS, 4.4(KitKat)
Color OS 3.0, Android 5.1, 6.0

Release Date
July 1, 2013
February 2013
December 12, 2012
June 27, 2012
December 2012
December 2012
October 2012
September 2013
October 2012
December 2013
March 2014
May 2014
October 2014
December 2014
May 2015
August 2015
September 2015
December 2015
January 2016
August 2016
May 2015
July 4, 2016

text: Blu-ray players[edit]

text: Oppo's first universal Blu-ray Disc player was the BDP-83.[26][27][28][29]

text: The BDP-93 was released in 2010, featuring 3D compatibility and dual HDMI signal output.

text: This was followed by the BDP-95 whose video performance is identical in all respects with the BDP-93, but with an improved analogue audio output section.[30]

text: The BDP-103 and BDP-105 models were released near the end of 2012, featuring dual HDMI signal input in addition to dual HDMI signal output. T

text: The BDP-103D was released in October 2013. This new model is the first Blu-ray player worldwide featuring Darbee Visual Presence technology.

text: At the end of 2016 Oppo introduced their first 4K/UHD BluRay player, the 203. Backwards compatible (as with previous machines), the 203 supports playback of Ultra High Definition discs, along with HDR (high dynamic range) and Dolby Vision capability.

text: This was followed in 2017 by the 205 - similar to the 203 but, as with previous "5" designated players, had added audiophile features.

text: Headphones & amplifiers[edit]

text: In 2014 OPPO released a number of high end headphones and amplifiers. The flagship PM-1 and PM-2 headphones along with the HA-1 desktop amplifier have been heavily promoted in the audio community. One blogger declares the PM-2 is "near to perfect".[31]

text: Released in 2015, the HA-2, was a portable version of the HA-1 amp/DAC which featured a battery pack option as well as a stitched leather casing. The phone played music in real-time to the HA-2 (via the included Android or iOS micro USB cable, or USB cable if from PC). It also can be charged using an included "rapid charger" charging kit. The battery pack feature can only be used simultaneously while the HA-2 is used to play music if the playing (source) device is an Apple iOS device. In October 2016 an updated version was released with a new DAC chip and now named HA-2SE. Otherwise it was the same as the HA-2[citation needed]


document_title: Jimmy John's

question_text: how many jimmy johns are there in the us

text: Jimmy John's

text: History[edit]

text: After Jimmy John Liautaud graduated second to last in his class at Elgin Academy (1982), his father gave him the choice to join the military or start a business.[6] Liautaud chose the latter, and his father lent him $25,000 to start a hot dog business, with the son owning 52% of the business, and his father owning 48%.[7] He soon realized that a hot dog business would cost more than he had, so he decided to open a sandwich shop.[8][9]

text: On January 13, 1983, the first Jimmy John's opened in a garage in Charleston, Illinois. Paying $200 a month in rent, Liautaud could only afford used equipment consisting of a refrigerator, a chest freezer, an oven, and a meat slicer.[10]

text: The store was able to realize a profit its first year of business, despite the poor location of the store, due to Jimmy John’s willingness to deliver his sandwiches to the nearby dorms at Eastern Illinois University, as well as his handing out free samples for marketing purposes.[3][8]

text: In April 1985, Liautaud bought out his father's interest in the business, becoming the sole owner. In 1986, he opened his second store in Macomb, Illinois, and in 1987, he opened a third in Champaign, Illinois.

text: In 1988, Liautaud met Jamie Coulter, who would later become the CEO of Lone Star Steakhouse & Saloon. Coulter mentored Liautaud and “taught [him] how to effectively run multiple units.”[8]

text: Liautaud continued opening more stores and developed a prototype before beginning franchising in 1994. Franchising continued until 2002 when Liautaud stopped selling franchises for one year to give support for stores that were struggling.[11] The first franchise store opened in Eau Claire, Wisconsin. In 2001, the hundredth Jimmy John's store opened in Mt. Pleasant, Michigan. In 2007, the five-hundredth store opened in Seattle, Washington, and in 2010, the thousandth opened in Beaverton, Oregon.[12]

text: As of March 2017, Jimmy John's has almost 3,000 stores with plans for expansion up to 5,000 and beyond.[13]

text: CNNMoney listed Jimmy John’s as one of ten “Great Franchise Bets.” The company estimates that annual sales can be as high as $1.2 million while net profits can average at about $280,000. Real estate start-up costs are estimated to be between $305,000 and $485,500.[10]

text: Liautaud realized that in order to grow he would need help acquiring better locations for his stores. Since he had little expertise in real estate, he decided to take on a partner who did. In January 2007, Liautaud sold a 33% stake to Weston Presidio, a San Francisco-based private-equity firm.[14] In the first year after partnering with Weston Presidio, 100 real estate deals were closed.[8]

text: The company has completed two recapitalizations since Weston Presidio's investment.[15]

text: In the summer of 2015, pictures of Liautaud posing with big game circulated on social media, leading to increased calls to boycott his restaurants. In an interview in 2015 with the Chicago Tribune, Liautaud said, "I don't hunt big African game anymore."[3]

text: In September 2016, Jimmy John's announced that Roark Capital Group had agreed to acquire a majority stake in the company. Terms of the transaction were not immediately disclosed, though it was later clarified that Liautaud retained 35% ownership of the company as part of the deal.[16] As part of the agreement, the company's founder and largest individual shareholder Jimmy John Liautaud will continue as chairman of the board.[17][18]

text: Labor relations[edit]

text: In 2010, when the Industrial Workers of the World attempted to unionize ten Minneapolis locations, The New York Times called the effort "one of the few efforts to organize fast-food workers in American history."[19]

text: In October 2014, it was revealed that employees at Jimmy John's, including sandwich makers and delivery drivers, were required to sign non-compete agreements as a condition of employment.[20][21] The agreement restricted the employee from working for a competitor for two years, where a competitor was defined as a business which derives more than ten percent of its revenue from selling sandwiches and is located within three miles of any Jimmy John's. Additionally, the employee could not work for another Jimmy John's franchisee for a year.[22] Jimmy John’s has since settled lawsuits filed by the Attorneys General of New York & Illinois on this matter. In statements, the company clarified that it had taken steps to remove noncompete agreements from their new hire paperwork long before they were contacted by the Attorneys General, and that “Enforcement of noncompete agreements against our own hourly store employees is not a part of Jimmy John’s culture or business model.”[23]

text: Awards[edit]

text: Jimmy John's was named #1 on the Entrepreneur 2016 Franchise 500.[24] In 2014, YouGov BrandIndex ranked restaurant chains that have the highest millennial brand loyalty, and Jimmy John's topped the ranking with 83% of the vote based on restaurants they would consider going to again.[25] Jimmy John's was named the #2 Most Popular Restaurant for Business Meals by expense reporting program Certify.[26] In 2015, Entrepreneur.com named Jimmy John's one of the 10 Promising Franchises for Ambitious Entrepreneurs.[27] In March 2017, Jimmy John's won Franchise Times' "Deal of the Year" for attracting Roark Capital Group as the company's new majority owner. FT's judges called the deal "one of the best private equity deals of all time in the restaurant business."[28]

text: Sponsorships[edit]

text: Starting in 2007, Jimmy John's began sponsoring NASCAR, first with Steven Wallace in 2007 and 2008. In 2009 and 2010, Jimmy John's sponsored Kevin Harvick in the NASCAR Nationwide Series.[29] In 2011, Jimmy John's and Richard Childress Racing reached a multi-year agreement to sponsor Harvick for the Sprint Cup Series. The 2014 sponsorship continued with Harvick and the Stewart-Haas Racing team.[30] On September 13, 2014, Jimmy John's became the title sponsor of the Jimmy John's Freaky Fast 300 at Chicagoland Speedway.[31] Kevin Harvick won the 2014 NASCAR Sprint Cup Championship giving Jimmy John's their first championship.

text: In 2010, Jimmy John's entered an Ultimate Fighting Championship sponsorship with Brock Lesnar. Lesnar returned to the WWE in 2012 and continued his sponsorship with Jimmy John's.[32]

text: In 2015, Jimmy John's co-sponsored the RCH Factory Racing Supercross and Motocross team featuring Ken Roczen. The team contested both the Monster Energy AMA Supercross and the Lucas Oil Pro Motocross championships.[33] In June, Jimmy John's sponsored former NASCAR champion Rusty Wallace for his Speed Energy Formula Off-Road debut at the 2015 X Games.[34]

text: In June 2015, it was announced that Jimmy John’s purchased the naming rights to the Utica, Michigan baseball stadium which is the current home of the three teams in the newly formed United Shore Professional Baseball League.[35] Jimmy John’s Field opened on May 30, 2016.[36][37]

text: Other Jimmy John's sponsorships include the Boston Red Sox, Chicago Blackhawks, Detroit Red Wings, Houston Astros, Nashville Predators, Seattle Mariners and the GoDaddy.com Bowl among many others.[38]


document_title: Iodine

question_text: where is iodine found in the periodic table

question_tokens: where is iodine found in the periodic table

text: Iodine

text: History[edit]

text: In 1811, iodine was discovered by French chemist Bernard Courtois,[5][6] who was born to a manufacturer of saltpeter (an essential component of gunpowder). At the time of the Napoleonic Wars, saltpeter was in great demand in France. Saltpeter produced from French nitre beds required sodium carbonate, which could be isolated from seaweed collected on the coasts of Normandy and Brittany. To isolate the sodium carbonate, seaweed was burned and the ash washed with water. The remaining waste was destroyed by adding sulfuric acid. Courtois once added excessive sulfuric acid and a cloud of purple vapour rose. He noted that the vapour crystallised on cold surfaces, making dark crystals.[7] Courtois suspected that this material was a new element but lacked funding to pursue it further.[8]

text: Courtois gave samples to his friends, Charles Bernard Desormes (1777–1838) and Nicolas Clément (1779–1841), to continue research. He also gave some of the substance to chemist Joseph Louis Gay-Lussac (1778–1850), and to physicist André-Marie Ampère (1775–1836). On 29 November 1813, Desormes and Clément made Courtois' discovery public. They described the substance to a meeting of the Imperial Institute of France.[9] On 6 December, Gay-Lussac announced that the new substance was either an element or a compound of oxygen.[10][11][12] It was Gay-Lussac who suggested the name "iode", from the Greek word ἰοειδής[13] (ioeidēs) for violet (because of the colour of iodine vapor).[5][10] Ampère had given some of his sample to English chemist Humphry Davy (1778–1829), who experimented on the substance and noted its similarity to chlorine.[14] Davy sent a letter dated 10 December to the Royal Society of London stating that he had identified a new element.[15] Arguments erupted between Davy and Gay-Lussac over who identified iodine first, but both scientists acknowledged Courtois as the first to isolate the element.[8]

text: Properties[edit]

text: Iodine is the fourth halogen, being a member of group 17 in the periodic table, below fluorine, chlorine, and bromine; it is the heaviest stable member of its group. (The scarce and fugitive fifth halogen, the radioactive astatine, is not well-studied due to its expense and inaccessibility in large quantities, but appears to show various unusual properties due to relativistic effects.) Iodine has an electron configuration of [Kr]4d105s25p5, with the seven electrons in the fifth and outermost shell being its valence electrons. Like the other halogens, it is one electron short of a full octet and is hence a strong oxidising agent, reacting with many elements in order to complete its outer shell, although in keeping with periodic trends, it is the weakest oxidising agent among the stable halogens: it has the lowest electronegativity among them, just 2.66 on the Pauling scale (compare fluorine, chlorine, and bromine at 3.98, 3.16, and 2.96 respectively; astatine continues the trend with an electronegativity of 2.2). Elemental iodine hence forms diatomic molecules with chemical formula I2, where two iodine atoms share a pair of electrons in order to each achieve a stable octet for themselves; at high temperatures, these diatomic molecules reversibly dissociate a pair of iodine atoms. Similarly, the iodide anion, I−, is the strongest reducing agent among the stable halogens, being the most easily oxidised back to diatomic I2.[16] (Astatine goes further, being indeed unstable as At− and readily oxidised to At0 or At+, although the existence of At2 is not settled.)[17]

text: The halogens darken in colour as the group is descended: fluorine is a very pale yellow gas, chlorine is greenish-yellow, and bromine is a reddish-brown volatile liquid. Iodine conforms to the prevailing trend, being a shiny black crystalline solid that melts at 114 °C and boils at 183 °C to form a violet gas. This trend occurs because the wavelengths of visible light absorbed by the halogens increase down the group (though astatine may not conform to it, depending on how metallic it turns out to be).[16] Specifically, the violet colour of iodine gas results from the electron transition between the highest occupied antibonding πg molecular orbital and the lowest vacant antibonding σu molecular orbital.[18]

text: Elemental iodine is slightly soluble in water, with one gram dissolving in 3450 ml at 20 °C and 1280 ml at 50 °C; potassium iodide may be added to increase solubility via formation of triiodide ions, among other polyiodides.[18] Nonpolar solvents such as hexane and carbon tetrachloride provide a higher solubility.[19] Polar solutions, such as aqueous solutions, are brown, reflecting the role of these solvents as Lewis bases; on the other hand, nonpolar solutions are violet, the color of iodine vapour.[18] Charge-transfer complexes form when iodine is dissolved in polar solvents, hence changing the colour. Iodine is violet when dissolved in carbon tetrachloride and saturated hydrocarbons but deep brown in alcohols and amines, solvents that form charge-transfer adducts.[20]

text: The melting and boiling points of iodine are the highest among the halogens, conforming to the increasing trend down the group, since iodine has the largest electron cloud among them that is the most easily polarised, resulting in its molecules having the strongest van der Waals interactions among the halogens. Similarly, iodine is the least volatile of the halogens.[16] Because it has the largest atomic radius among the halogens, iodine has the lowest first ionisation energy, lowest electron affinity, lowest electronegativity and lowest reactivity of the halogens.[16]

text: The interhalogen bond in diiodine is the weakest of all the halogens. As such, 1% of a sample of gaseous iodine at atmospheric pressure is dissociated into iodine atoms at 575 °C. Temperatures greater than 750 °C are required for fluorine, chlorine, and bromine to dissociate to a similar extent. Most bonds to iodine are weaker than the analogous bonds to the lighter halogens.[16] Gaseous iodine is composed of I2 molecules with an I–I bond length of 266.6 pm. The I–I bond is one of the longest single bonds known. It is even longer (271.5 pm) in solid orthorhombic crystalline iodine, which has the same crystal structure as chlorine and bromine. (The record is held by iodine's neighbour xenon: the Xe–Xe bond length is 308.71 pm.)[22] As such, within the iodine molecule, significant electronic interactions occur with the two next-nearest neighbours of each atom, and these interactions give rise, in bulk iodine, to a shiny appearance and semiconducting properties.[16] Iodine is a two-dimensional semiconductor with a band gap of 1.3 eV (125 kJ/mol): it is a semiconductor in the plane of its crystalline layers and an insulator in the perpendicular direction.[16]

text: Isotopes[edit]

text: Of the thirty-seven known isotopes of iodine, only one occurs in nature, iodine-127. The others are radioactive and have half-lives too short to be primordial. As such, iodine is monoisotopic and its atomic weight is known to great precision, as it is a constant of nature.[16]

text: The longest-lived of the radioactive isotopes of iodine is iodine-129, which has a half-life of 15.7 million years, decaying via beta decay to stable xenon-129.[23] Some iodine-129 was formed along with iodine-127 before the formation of the Solar System, but it has by now completely decayed away, making it an extinct radionuclide that is nevertheless still useful in dating the history of the early Solar System or very old groundwaters, due to its mobility in the environment. Its former presence may be determined from an excess of its daughter xenon-129.[24][25][26][27][28] Traces of iodine-129 still exist today, as it is also a cosmogenic nuclide, formed from cosmic ray spallation of atmospheric xenon: these traces make up 10−14 to 10−10 of all terrestrial iodine. It also occurs from open-air nuclear testing, and is not hazardous because of its incredibly long half-life, the longest of all fission products. At the peak of thermonuclear testing in the 1960s and 1970s, iodine-129 still made up only about 10−7 of all terrestrial iodine.[29] Excited states of iodine-127 and iodine-129 are often used in Mössbauer spectroscopy.[16]

text: The other iodine radioisotopes have much shorter half-lives, no longer than days.[23] Some of them have medical applications involving the thyroid gland, where the iodine that enters the body is stored and concentrated. Iodine-123 has a half-life of thirteen hours and decays by electron capture to tellurium-123, emitting gamma radiation; it is used in nuclear medicine imaging, including single photon emission computed tomography (SPECT) and X-ray computed tomography (X-Ray CT) scans.[30] Iodine-125 has a half-life of fifty-nine days, decaying by electron capture to tellurium-125 and emitting low-energy gamma radiation; the second-longest-lived iodine radioisotope, it has uses in biological assays, nuclear medicine imaging and in radiation therapy as brachytherapy to treat a number of conditions, including prostate cancer, uveal melanomas, and brain tumours.[31] Finally, iodine-131, with a half-life of eight days, beta decays to an excited state of stable xenon-131 that then converts to the ground state by emitting gamma radiation. It is a common fission product and thus is present in high levels in radioactive fallout. It may then be absorbed through contaminated food, and will also accumulate in the thyroid. As it decays, it may cause damage to the thyroid. The primary risk from exposure to high levels of iodine-131 is the chance occurrence of radiogenic thyroid cancer in later life. Other risks include the possibility of non-cancerous growths and thyroiditis.[32]

text: The usual means of protection against the negative effects of iodine-131 is by saturating the thyroid gland with stable iodine-127 in the form of potassium iodide tablets, taken daily for optimal prophylaxis.[33] However, iodine-131 may also be used for medicinal purposes in radiation therapy for this very reason, when tissue destruction is desired after iodine uptake by the tissue.[34] Iodine-131 is also used as a radioactive tracer.[35][36][37][38]

text: Chemistry and compounds[edit]

text:
Halogen bond energies (kJ/mol)[18]

X
XX
HX
BX3
AlX3
CX4

F
159
574
645
582
456

Cl
243
428
444
427
327

Br
193
363
368
360
272

I
151
294
272
285
239

text: Though it is the least reactive of the halogens, iodine is still one of the more reactive elements. For example, while chlorine gas will halogenate carbon monoxide, nitrogen monoxide, and sulfur dioxide to phosgene, nitrosyl chloride, and sulfuryl chloride respectively, iodine will not do so. Furthermore, iodination of metals tends to result in lower oxidation states than chlorination or bromination; for example, rhenium metal reacts with chlorine to form rhenium hexachloride, but with bromine it forms only rhenium pentabromide and iodine can achieve only rhenium tetraiodide.[16] By the same token, however, since iodine has the lowest ionisation energy among the halogens and is the most easily oxidised of them, it has a more significant cationic chemistry and its higher oxidation states are rather more stable than those of bromine and chlorine, for example in iodine heptafluoride.[18]

text: Hydrogen iodide[edit]

text: The simplest compound of iodine is hydrogen iodide, HI. It is a colourless gas that reacts with oxygen to give water and iodine. Although it is useful in iodination reactions in the laboratory, it does not have large-scale industrial uses, unlike the other hydrogen halides. Commercially, it is usually made by reacting iodine with hydrogen sulfide or hydrazine:[39]

text: At room temperature, it is a colourless gas, like all of the hydrogen halides except hydrogen fluoride, since hydrogen cannot form strong hydrogen bonds to the large and only mildly electronegative iodine atom. It melts at −51.0 °C and boils at −35.1 °C. It is an endothermic compound that can exothermically dissociate at room temperature, although the process is very slow unless a catalyst is present: the reaction between hydrogen and iodine at room temperature to give hydrogen iodide does not proceed to completion. The H–I bond dissociation energy is likewise the smallest of the hydrogen halides, at 295 kJ/mol.[40]

text: Aqueous hydrogen iodide is known as hydroiodic acid, which is a strong acid. Hydrogen iodide is exceptionally soluble in water: one litre of water will dissolve 425 litres of hydrogen iodide, and the saturated solution has only four water molecules per molecule of hydrogen iodide.[41] Commercial so-called "concentrated" hydroiodic acid usually contains 48–57% HI by mass; the solution forms an azeotrope with boiling point 126.7 °C at 56.7 g HI per 100 g solution. Hence hydroiodic acid cannot be concentrated past this point by evaporation of water.[40]

text:
Unlike hydrogen fluoride, anhydrous liquid hydrogen iodide is difficult to work with as a solvent, because its boiling point is low, it has a small liquid range, its dielectric constant is low and it does not dissociate appreciably into H2I+ and HI−
2 ions – the latter, in any case, are much less stable than the bifluoride ions (HF−
2) due to the very weak hydrogen bonding between hydrogen and iodine, though its salts with very large and weakly polarising cations such as Cs+ and NR+
4 (R = Me, Et, Bun) may still be isolated. Anhydrous hydrogen iodide is a poor solvent, able to dissolve only small molecular compounds such as nitrosyl chloride and phenol, or salts with very low lattice energies such as tetraalkylammonium halides.[40]

text: Other binary iodides[edit]

text: Nearly all elements in the periodic table form binary iodides. The exceptions are decidedly in the minority and stem in each case from one of three causes: extreme inertness and reluctance to participate in chemical reactions (the noble gases); extreme nuclear instability hampering chemical investigation before decay and transmutation (many of the heaviest elements beyond bismuth); and having an electronegativity higher than iodine's (oxygen and the first three halogens), so that the resultant binary compounds are formally not iodides but rather oxides or halides of iodine.[42]

text: Given the large size of the iodide anion and iodine's weak oxidising power, high oxidation states are difficult to achieve in binary iodides, the maximum known being in the pentaiodides of niobium, tantalum, and protactinium. Iodides can be made by reaction of an element or its oxide, hydroxide, or carbonate with hydroiodic acid, and then dehydrated by mildly high temperatures combined with either low pressure or anhydrous hydrogen iodide gas. These methods work best when the iodide product is stable to hydrolysis; otherwise, the possibilities include high-temperature oxidative iodination of the element with iodine or hydrogen iodide, high-temperature iodination of a metal oxide or other halide by iodine, a volatile metal halide, carbon tetraiodide, or an organic iodide. For example, molybdenum(IV) oxide reacts with aluminium(III) iodide at 230 °C to give molybdenum(II) iodide. An example involving halogen exchange is given below, involving the reaction of tantalum(V) chloride with excess aluminium(III) iodide at 400 °C to give tantalum(V) iodide:[42]

text: Lower iodides may be produced either through thermal decomposition or disproportionation, or by reducing the higher iodide with hydrogen or a metal, for example:[42]

text: Most of the iodides of the pre-transition metals (groups 1, 2, and 3, along with the lanthanides and actinides in the +2 and +3 oxidation states) are mostly ionic, while nonmetals tend to form covalent molecular iodides, as do metals in high oxidation states from +3 and above. Ionic iodides MIn tend to have the lowest melting and boiling points among the halides MXn of the same element, because the electrostatic forces of attraction between the cations and anions are weakest for the large iodide anion. In contrast, covalent iodides tend to instead have the highest melting and boiling points among the halides of the same element, since iodine is the most polarisable of the halogens and, having the most electrons among them, can contribute the most to van der Waals forces. Naturally, exceptions abound in intermediate iodides where one trend gives way to the other. Similarly, solubilities in water of predominantly ionic iodides (e.g. potassium and calcium) are the greatest among ionic halides of that element, while those of covalent iodides (e.g. silver) are the lowest of that element. In particular, silver iodide is very insoluble in water and its formation is often used as a qualitative test for iodine.[42]

text: Iodine halides[edit]

text:
The halogens form many binary, diamagnetic interhalogen compounds with stoichiometries XY, XY3, XY5, and XY7 (where X is heavier than Y), and iodine is no exception. Iodine forms all three possible diatomic interhalogens, a trifluoride and trichloride, as well as a pentafluoride and, exceptionally among the halogens, a heptafluoride. Numerous cationic and anionic derivatives are also characterised, such as the wine-red or bright orange compounds of ICl+
2 and the dark brown or purplish black compounds of I2Cl+. Apart from these, some pseudohalides are also known, such as cyanogen iodide (ICN), iodine thiocyanate (ISCN), and iodine azide (IN3).[43]

text:
Iodine monofluoride (IF) is unstable at room temperature and disproportionates very readily and irreversibly to iodine and iodine pentafluoride, and thus cannot be obtained pure. It can be synthesised from the reaction of iodine with fluorine gas in trichlorofluoromethane at −45 °C, with iodine trifluoride in trichlorofluoromethane at −78 °C, or with silver(I) fluoride at 0 °C.[43] Iodine monochloride (ICl) and iodine monobromide (IBr), on the other hand, are moderately stable. The former, a volatile red-brown compound, was discovered independently by Joseph Louis Gay-Lussac and Humphry Davy in 1813–4 not long after the discoveries of chlorine and iodine, and it mimics the intermediate halogen bromine so well that Justus von Liebig was misled into mistaking bromine (which he had found) for iodine monochloride. Iodine monochloride and iodine monobromide may be prepared simply by reacting iodine with chlorine or bromine at room temperature and purified by fractional crystallisation. Both are quite reactive and attack even platinum and gold, though not boron, carbon, cadmium, lead, zirconium, niobium, molybdenum, and tungsten. Their reaction with organic compounds depends on conditions. Iodine chloride vapour tends to chlorinate phenol and salicyclic acid, since when iodine chloride undergoes homolytic dissociation, chlorine and iodine are produced and the former is more reactive. However, iodine chloride in tetrachloromethane solution results in iodination being the main reaction, since now heterolytic fission of the I–Cl bond occurs and I+ attacks phenol as an electrophile. However, iodine monobromide tends to brominate phenol even in tetrachloromethane solution because it tends to dissociate into its elements in solution, and bromine is more reactive than iodine.[43] When liquid, iodine monochloride and iodine monobromide dissociate into I
2X+ and IX−
2 anions (X = Cl, Br); thus they are significant conductors of electricity and can be used as ionising solvents.[43]

text:
Iodine trifluoride (IF3) is an unstable yellow solid that decomposes above −28 °C. It is thus little-known. It is difficult to produce because fluorine gas would tend to oxidise iodine all the way to the pentafluoride; reaction at low temperature with xenon difluoride is necessary. Iodine trichloride, which exists in the solid state as the planar dimer I2Cl6, is a bright yellow solid, synthesised by reacting iodine with liquid chlorine at −80 °C; caution is necessary during purification because it easily dissociates to iodine monochloride and chlorine and hence can act as a strong chlorinating agent. Liquid iodine trichloride conducts electricity, possibly indicating dissociation to ICl+
2 and ICl−
4 ions.[44]

text:
Iodine pentafluoride (IF5), a colourless, volatile liquid, is the most thermodynamically stable iodine fluoride, and can be made by reacting iodine with fluorine gas at room temperature. It is a fluorinating agent, but is mild enough to store in glass apparatus. Again, slight electrical conductivity is present in the liquid state because of dissociation to IF+
4 and IF−
6. The pentagonal bipyramidal iodine heptafluoride (IF7) is an extremely powerful fluorinating agent, behind only chlorine trifluoride, chlorine pentafluoride, and bromine pentafluoride among the interhalogens: it reacts with almost all the elements even at low temperatures, fluorinates Pyrex glass to form iodine(VII) oxyfluoride (IOF5), and sets carbon monoxide on fire.[45]

text: Iodine oxides and oxoacids[edit]

text: Iodine oxides are the most stable of all the halogen oxides, because of the strong I–O bonds resulting from the large electronegativity difference between iodine and oxygen, and they have been known for the longest time.[20] The stable, white, hygroscopic iodine pentoxide (I2O5) has been known since its formation in 1813 by Gay-Lussac and Davy. It is most easily made by the dehydration of iodic acid (HIO3), which it is the anhydride of. It will quickly oxidise carbon monoxide completely to carbon dioxide at room temperature, and is thus a useful reagent in determining carbon monoxide concentration. It also oxidises nitrogen oxide, ethylene, and hydrogen sulfide. It reacts with sulfur trioxide and peroxydisulfuryl difluoride (S2O6F2) to form salts of the iodyl cation, [IO2]+, and is reduced by concentrated sulfuric acids to iodosyl salts involving [IO]+. It may be fluorinated by fluorine, bromine trifluoride, sulfur tetrafluoride, or chloryl fluoride, resulting iodine pentafluoride, which also reacts with iodine pentoxide, giving iodine(V) oxyfluoride, IOF3. A few other less stable oxides are known, notably I4O9 and I2O4; their structures have not been determined, but reasonable guesses are IIII(IVO3)3 and [IO]+[IO3]− respectively.[46]

text:
Standard reduction potentials for aqueous I species[47]

E°(couple)
a(H+) = 1
(acid)
E°(couple)
a(OH−) = 1
(base)

I2/I−
+0.535
I2/I−
+0.535

HOI/I−
+0.987
IO−/I−
+0.48

IO−
3/I−
+0.26

HOI/I2
+1.439
IO−/I2
+0.42

IO−
3/I2
+1.195

IO−
3/HOI
+1.134
IO−
3/IO−
+0.15

IO−
4/IO−
3
+1.653

H5IO6/IO−
3
+1.601
H
3IO2−
6/IO−
3
+0.65

text: More important are the four oxoacids: hypoiodous acid (HIO), iodous acid (HIO2), iodic acid (HIO3), and periodic acid (HIO4 or H5IO6). When iodine dissolves in aqueous solution, the following reactions occur:[47]

text:
I2 + H2O
⇌ HIO + H+ + I−
Kac = 2.0 × 10−13 mol2 l−2

I2 + 2 OH−
⇌ IO− + H2O + I−
Kalk = 30 mol−1 l

text: Hypoiodous acid is unstable to disproportionation. The hypoiodite ions thus formed disproportionate immediately to give iodide and iodate:[47]

text:
3 IO− ⇌ 2 I− + IO−
3
K = 1020

text: Iodous acid and iodite are even less stable and exist only as a fleeting intermediate in the oxidation of iodide to iodate, if at all.[47] Iodates are by far the most important of these compounds, which can be made by oxidising alkali metal iodides with oxygen at 600 °C and high pressure, or by oxidising iodine with chlorates. Unlike chlorates, which disproportionate very slowly to form chloride and perchlorate, iodates are stable to disproportionation in both acidic and alkaline solutions. From these, salts of most metals can be obtained. Iodic acid is most easily made by oxidation of an aqueous iodine suspension by electrolysis or fuming nitric acid. Iodate has the weakest oxidising power of the halates, but reacts the quickest.[48]

text:
Many periodates are known, including not only the expected tetrahedral IO−
4, but also square-pyramidal IO3−
5, octahedral orthoperiodate IO5−
6, [IO3(OH)3]2−, [I2O8(OH2)]4−, and I
2O4−
9. They are usually made by oxidising alkaline sodium iodate electrochemically (with lead(IV) oxide as the anode) or by chlorine gas:[49]

text:
They are thermodymically and kinetically powerful oxidising agents, quickly oxidising Mn2+ to MnO−
4, and cleaving glycols, α-diketones, α-ketols, α-aminoalcohols, and α-diamines.[49] Orthoperiodate especially stabilises high oxidation states among metals because of its very high negative charge of −5. Orthoperiodic acid, H5IO6, is stable, and dehydrates at 100 °C in a vacuum to metaperiodic acid, HIO4. Attempting to go further does not result in the nonexistent iodine heptoxide (I2O7), but rather iodine pentoxide and oxygen. Periodic acid may be protonated by sulfuric acid to give the I(OH)+
6 cation, isoelectronic to Te(OH)6 and Sb(OH)−
6, and giving salts with bisulfate and sulfate.[20]

text: Polyiodine compounds[edit]

text:
When iodine dissolves in strong acids, such as fuming sulfuric acid, a bright blue paramagnetic solution including I+
2 cations is formed. A solid salt of the diiodine cation may be obtained by oxidising iodine with antimony pentafluoride:[20]

text:
The salt I2Sb2F11 is dark blue, and the blue tantalum analogue I2Ta2F11 is also known. Whereas the I–I bond length in I2 is 267 pm, that in I+
2 is only 256 pm as the missing electron in the latter has been removed from an antibonding orbital, making the bond stronger and hence shorter. In fluorosulfuric acid solution, deep-blue I+
2 reversibly dimerises below −60 °C, forming red rectangular diamagnetic I2+
4. Other polyiodine cations are not as well-characterised, including bent dark-brown or black I+
3 and centrosymmetric C2h green or black I+
5, known in the AsF−
6 and AlCl−
4 salts among others.[20][50]

text:
The only important polyiodide anion in aqueous solution is linear triiodide, I−
3. Its formation explains why the solubility of iodine in water may be increased by the addition of potassium iodide solution:[20]

text:
Many other polyiodides may be found when solutions containing iodine and iodide crystallise, such as I−
5, I−
9, I2−
4, and I2−
8, whose salts with large, weakly polarising cations such as Cs+ may be isolated.[20][51]

text: Organoiodine compounds[edit]

text: Organoiodine compounds have been fundamental in the development of organic synthesis, such as in the Hofmann elimination of amines,[52] the Williamson ether synthesis,[53] the Wurtz coupling reaction,[54] and in Grignard reagents.[55]

text: The carbon–iodine bond is a common functional group that forms part of core organic chemistry; formally, these compounds may be thought of as organic derivatives of the iodide anion. The simplest organoiodine compounds, alkyl iodides, may be synthesised by the reaction of alcohols with phosphorus triiodide; these may then be used in nucleophilic substitution reactions, or for preparing Grignard reagents. The C–I bond is the weakest of all the carbon–halogen bonds due to the minuscule difference in electronegativity between carbon (2.55) and iodine (2.66). As such, iodide is the best leaving group among the halogens, to such an extent that many organoiodine compounds turn yellow when stored over time due to decomposition into elemental iodine; as such, they are commonly used in organic synthesis, because of the easy formation and cleavage of the C–I bond.[56] They are also significantly denser than the other organohalogen compounds thanks to the high atomic weight of iodine.[57] A few organic oxidising agents like the iodanes contain iodine in a higher oxidation state than −1, such as 2-iodoxybenzoic acid, a common reagent for the oxidation of alcohols to aldehydes,[58] and iodobenzene dichloride (PhICl2), used for the selective chlorination of alkenes and alkynes.[59] One of the more well-known uses of organoiodine compounds is the so-called iodoform test, where iodoform (CHI3) is produced by the exhaustive iodination of a methyl ketone (or another compound capable of being oxidised to a methyl ketone), as follows:[60]

text: Some drawbacks of using organoiodine compounds as compared to organochlorine or organobromine compounds is the greater expense and toxicity of the iodine derivatives, since iodine is expensive and organoiodine compounds are stronger alkylating agents.[61] For example, iodoacetamide and iodoacetic acid denature proteins by irreversibly alkylating cysteine residues and preventing the reformation of disulfide linkages.[62]

text: Halogen exchange to produce iodoalkanes by the Finkelstein reaction is slightly complicated by the fact that iodide is a better leaving group than chloride or bromide. The difference is nevertheless small enough that the reaction can be driven to completion by exploiting the differential solubility of halide salts, or by using a large excess of the halide salt.[60] In the classic Finkelstein reaction, an alkyl chloride or an alkyl bromide is converted to an alkyl iodide by treatment with a solution of sodium iodide in acetone. Sodium iodide is soluble in acetone and sodium chloride and sodium bromide are not.[63] The reaction is driven toward products by mass action due to the precipitation of the insoluble salt.[64][65]

text: Occurrence and production[edit]

text: Iodine is the least abundant of the stable halogens, comprising only 0.46 parts per million of Earth's crustal rocks (compare: fluorine 544 ppm, chlorine 126 ppm, bromine 2.5 ppm). Among the eighty-four elements which occur in significant quantities (elements 1–42, 44–60, 62–83, and 90–92), it ranks sixty-first in abundance.[66] Iodide minerals are rare, and most deposits that are concentrated enough for economical extraction are iodate minerals instead. Examples include lautarite, Ca(IO3)2, and dietzeite, 7Ca(IO3)2·8CaCrO4.[66] These are the minerals that occur as trace impurities in the caliche, found in Chile, whose main product is sodium nitrate. In total, they can contain at least 0.02% and at most 1% iodine by weight.[67] Sodium iodate is extracted from the caliche and reduced to iodide by sodium bisulfite. This solution is then reacted with freshly extracted iodate, resulting in comproportionation to iodine, which may be filtered off.[16]

text: The caliche was the main source of iodine in the 19th century and continues to be important today, replacing kelp (which is no longer an economically viable source),[68] but in the late 20th century brines emerged as a comparable source. The Japanese Minami Kanto gas field east of Tokyo and the American Anadarko Basin gas field in northwest Oklahoma are the two largest such sources. The brine is hotter than 60 °C from the depth of the source. The brine is first purified and acidified using sulfuric acid, then the iodide present is oxidised to iodine with chlorine. An iodine solution is produced, but is dilute and must be concentrated. Air is blown into the solution to evaporate the iodine, which is passed into an absorbing tower where sulfur dioxide reduces the iodine. The hydrogen iodide (HI) is reacted with chlorine to precipitate the iodine. After filtering and purification the iodine is packed.[67][69]

text: These sources ensure that Chile and Japan are the largest producers of iodine today.[66] Alternatively, the brine may be treated with silver nitrate to precipitate out iodine as silver iodide, which is then decomposed by reaction with iron to form metallic silver and a solution of iron(II) iodide. The iodine may then be liberated by displacement with chlorine.[70]

text: Applications[edit]

text: Unlike chlorine and bromine which have one significant main use dwarfing all others, iodine is used in many applications of varying importance. About half of all produced iodine goes into various organoiodine compounds; another 15% remains as the pure element, another 15% is used to form potassium iodide, and another 15% for other inorganic iodine compounds. The remaining 5% is for minor uses. Among the major uses of iodine compounds are catalysts, animal feed supplements, stabilisers, dyes, colourants and pigments, pharmaceutical, sanitation (from tincture of iodine), and photography; minor uses include smog inhibition, cloud seeding, and various uses in analytical chemistry.[16]

text: Analysis[edit]

text: Potassium tetraiodomercurate(II), K2HgI4, is also known as Nessler's reagent. It is often used as a sensitive spot test for ammonia. Similarly, Cu2HgI4 is used as a precipitating reagent to test for alkaloids. The iodide and iodate anions are often used for quantitative volumetric analysis, for example in iodometry and the iodine clock reaction (in which iodine also serves as a test for starch, forming a dark blue complex),[16] and aqueous alkaline iodine solution is used in the iodoform test for methyl ketones.[60] The iodine test for starch is still used to detect counterfeit banknotes printed on starch-containing paper.[71]

text: Medicine[edit]

text: Elemental iodine[edit]

text: Elemental iodine is used as a disinfectant either as the element, or as the water-soluble triiodide anion I3− generated in situ by adding iodide to poorly water-soluble elemental iodine (the reverse chemical reaction makes some free elemental iodine available for antisepsis). Elemental iodine may also be used to treat iodine deficiency.[72]

text: In the alternative, iodine may be produced from iodophors, which contain iodine complexed with a solubilizing agent (iodide ion may be thought of loosely as the iodophor in triiodide water solutions). Examples of such preparations include:[73]

text:
Tincture of iodine: iodine in ethanol, or iodine and sodium iodide in a mixture of ethanol and water.
Lugol's iodine: iodine and iodide in water alone, forming mostly triiodide. Unlike tincture of iodine, Lugol's iodine has a minimised amount of the free iodine (I2) component.
Povidone iodine (an iodophor).

tag: ul

text: The antimicrobial action of iodine is quick and works at low concentrations, and thus it is used in operating theatres.[74] Its specific mode of action is unknown. It penetrates into microorganisms and attacks particular amino acids (such as cysteine and methionine), nucleotides, and fatty acids, ultimately resulting in cell death. It also has an antiviral action, but nonlipid viruses and parvoviruses are less sensitive than lipid enveloped viruses. Iodine probably attacks surface proteins of enveloped viruses, and it may also destabilise membrane fatty acids by reacting with unsaturated carbon bonds.[75]

text: Other formulations[edit]

text: In medicine, a saturated solution of potassium iodide is used to treat acute thyrotoxicosis. It is also used to block uptake of iodine-131 in the thyroid gland (see isotopes section above), when this isotope is used as part of radiopharmaceuticals (such as iobenguane) that are not targeted to the thyroid or thyroid-type tissues.[76][77]

text: Iodine-131 (usually as iodide) is a component of nuclear fallout, and is particularly dangerous owing to the thyroid gland's propensity to concentrate ingested iodine and retain it for periods longer than this isotope's radiological half-life of eight days. For this reason, people at risk of exposure to environmental radioactive iodine (iodine-131) in fallout may be instructed to take non-radioactive potassium iodide tablets. The typical adult dose is one 130 mg tablet per 24 hours, supplying 100 mg (100,000 micrograms) of ionic iodine. (The typical daily dose of iodine for normal health is of order 100 micrograms; see "Dietary Intake" below.) Ingestion of this large dose of non-radioactive iodine minimises the uptake of radioactive iodine by the thyroid gland.[78]

text: As an element with high electron density and atomic number, iodine absorbs X-rays weaker than 33.3 keV due to the photoelectric effect of the innermost electrons.[79] Organoiodine compounds are used with intravenous injection as X-ray radiocontrast agents. This application is often in conjunction with advanced X-ray techniques such as angiography and CT scanning. At present, all water-soluble radiocontrast agents rely on iodine.

text: Others[edit]

text: The production of ethylenediamine dihydroiodide, provided as a nutritional supplement for livestock, consumes a large portion of available iodine. Another significant use is a catalyst for the production of acetic acid by the Monsanto and Cativa processes. In these technologies, which support the world's demand for acetic acid, hydroiodic acid converts the methanol feedstock into methyl iodide, which undergoes carbonylation. Hydrolysis of the resulting acetyl iodide regenerates hydroiodic acid and gives acetic acid.[80]

text: Inorganic iodides find specialised uses. Titanium, zirconium, hafnium, and thorium are purified by the van Arkel process, which involves the reversible formation of the tetraiodides of these elements. Silver iodide is a major ingredient to traditional photographic film. Thousands of kilograms of silver iodide are used annually for cloud seeding to induce rain.[80]

text: The organoiodine compound erythrosine is an important food coloring agent. Perfluoroalkyl iodides are precursors to important surfactants, such as perfluorooctanesulfonic acid.[80]

text: Biological role[edit]

text: Iodine is an essential element for life and is the heaviest element commonly needed by living organisms. (Lanthanum and the other lanthanides, as well as tungsten, are used by a few microorganisms.)[81][82] It is required for the synthesis of the growth-regulating thyroid hormones thyroxine and triiodothyronine (T4 and T3 respectively, named after their number of iodine atoms). A deficiency of iodine leads to decreased production of T3 and T4 and a concomitant enlargement of the thyroid tissue in an attempt to obtain more iodine, causing the disease known as simple goitre. The major form of thyroid hormone in the blood is thyroxine (T4), which has a longer half-life than T3. In humans, the ratio of T4 to T3 released into the blood is between 14:1 and 20:1. T4 is converted to the active T3 (three to four times more potent than T4) within cells by deiodinases (5'-iodinase). These are further processed by decarboxylation and deiodination to produce iodothyronamine (T1a) and thyronamine (T0a'). All three isoforms of the deiodinases are selenium-containing enzymes; thus dietary selenium is essential for T3 production.[83]

text: Iodine accounts for 65% of the molecular weight of T4 and 59% of T3. Fifteen to 20 mg of iodine is concentrated in thyroid tissue and hormones, but 70% of all iodine in the body is found in other tissues, including mammary glands, eyes, gastric mucosa, fetal thymus, cerebro-spinal fluid and choroid plexus, arterial walls, the cervix, and salivary glands. In the cells of those tissues, iodide enters directly by sodium-iodide symporter (NIS). The action of iodine in mammary tissue is related to fetal and neonatal development, but in the other tissues, it is (at least) partially unknown.[84]

text: Dietary intake[edit]

text: Recommendations by the United States Institute of Medicine are between 110 and 130 µg for infants up to 12 months, 90 µg for children up to eight years, 130 µg for children up to 13 years, 150 µg for adults, 220 µg for pregnant women and 290 µg for lactation.[4][85] The Tolerable Upper Intake Level (UL) for adults is 1,100 μg/day.[86] This upper limit was assessed by analyzing the effect of supplementation on thyroid-stimulating hormone.[84]

text: The thyroid gland needs no more than 70 μg/day to synthesise the requisite daily amounts of T4 and T3.[4] The higher recommended daily allowance levels of iodine seem necessary for optimal function of a number of body systems, including lactating breast, gastric mucosa, salivary glands, brain cells, choroid plexus, thymus, and arterial walls.[4][87][88][89]

text: Natural sources of dietary iodine include seafood, such as fish, seaweeds (such as kelp) and shellfish, dairy products and eggs so long as the animals received enough iodine, and plants grown on iodine-rich soil.[90][91] Iodised salt is fortified with iodine in the form of sodium iodide.[91][92]

text: As of 2000, the median intake of iodine from food in the United States was 240 to 300 μg/day for men and 190 to 210 μg/day for women.[86] The general US population has adequate iodine nutrition,[93][94] with women of childbearing age and pregnant women having a possible mild risk of deficiency.[94] In Japan, consumption was considered much higher, ranging between 5,280 μg/day to 13,800 μg/day from dietary seaweed or kombu kelp,[84] often in the form of Kombu Umami extracts for soup stock and potato chips. However, new studies suggest that Japan's consumption is closer to 1,000–3,000 μg/day.[95] The adult UL in Japan was last revised to 3,000 µg/day in 2015.[96]

text: After iodine fortification programs such as iodisation of salt have been implemented, some cases of iodine-induced hyperthyroidism have been observed (so-called Jod-Basedow phenomenon). The condition seems to occur mainly in people over forty, and the risk appears higher when iodine deficiency is severe and the initial rise in iodine intake is high.[97]

text: Deficiency[edit]

text: In areas where there is little iodine in the diet,[98] typically remote inland areas and semi-arid equatorial climates where no marine foods are eaten, iodine deficiency gives rise to hypothyroidism, symptoms of which are extreme fatigue, goitre, mental slowing, depression, weight gain, and low basal body temperatures.[99] Iodine deficiency is the leading cause of preventable intellectual disability, a result that occurs primarily when babies or small children are rendered hypothyroidic by a lack of the element. The addition of iodine to table salt has largely eliminated this problem in the wealthier nations, but iodine deficiency remains a serious public health problem today in the developing world.[100] Iodine deficiency is also a problem in certain areas of Europe. Information processing, fine motor skills, and visual problem solving are improved by iodine repletion in moderately iodine-deficient children.[101]

text: Toxicity[edit]

text:
NFPA 704
fire diamond

1
2
1

Fire diamond hazard sign for elemental iodine[102]

text: Elemental iodine (I2) is toxic if taken orally undiluted. The lethal dose for an adult human is 30 mg/kg, which is about 2.1–2.4 grams for a human weighing 70 to 80 kg (even if experiments on rats demonstrated that these animals could survive after eating a 14000 mg/kg dose). Excess iodine can be more cytotoxic in the presence of selenium deficiency.[103] Iodine supplementation in selenium-deficient populations is, in theory, problematic, partly for this reason.[84] The toxicity derives from its oxidizing properties, through which it denaturates proteins (including enzymes).[104]

text: Elemental iodine is also a skin irritant, and direct contact with skin can cause damage and solid iodine crystals should be handled with care. Solutions with high elemental iodine concentration, such as tincture of iodine and Lugol's solution, are capable of causing tissue damage if used in prolonged cleaning or antisepsis; similarly, liquid Povidone-iodine (Betadine) trapped against the skin resulted in chemical burns in some reported cases.[105]

text: Occupational exposure[edit]

text: People can be exposed to iodine in the workplace by inhalation, ingestion, skin contact, and eye contact. The Occupational Safety and Health Administration (OSHA) has set the legal limit (Permissible exposure limit) for iodine exposure in the workplace at 0.1 ppm (1 mg/m3) during an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a Recommended exposure limit (REL) of 0.1 ppm (1 mg/m3) during an 8-hour workday. At levels of 2 ppm, iodine is immediately dangerous to life and health.[106]

text: Allergic reactions[edit]

text: Some people develop a hypersensitivity to products and foods containing iodine. Applications of tincture of iodine or Betadine can cause rashes, sometimes severe.[107] Parenteral use of iodine-based contrast agents (see above) can cause reactions ranging from a mild rash to fatal anaphylaxis. Such reactions have led to the misconception (widely held, even among physicians) that some people are allergic to iodine itself; even allergies to iodine-rich seafood have been so construed.[108] In fact, there has never been a confirmed report of a true iodine allergy, and an allergy to elemental iodine or simple iodide salts is theoretically impossible. Hypersensitivity reactions to products and foods containing iodine are apparently related to their other molecular components;[109] thus, a person who has demonstrated an allergy to one food or product containing iodine may not be have an allergic reaction to another. Patients with various food allergies (shellfish, egg, milk, etc.) or asthma are more likely to suffer reactions to contrast media containing iodine.[109] As with all medications, the patient's allergy history should be questioned and consulted before any containing iodine are administered.[110]