Iodine

II 2 iodinatediodoI 4 iodideiodine allergydeiodinateddiiodineI 3
Iodine is a chemical element with the symbol I and atomic number 53.wikipedia
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Halogen

halogensgroup 1717
The heaviest of the stable halogens, it exists as a lustrous, purple-black non-metallic solid at standard conditions that melts to form a deep violet liquid at 114 degrees Celsius, and boils to a violet gas at 184 degrees Celsius. 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).
The halogens are a group in the periodic table consisting of five chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).

Periodate

Orthoperiodatemetaperiodate
Iodine occurs in many oxidation states, including iodide (I − ), iodate, and the various periodate anions.
Periodate is an anion composed of iodine and oxygen.

Iodine deficiency

iodineiodine deficiency disordersIodine-deficiency
Iodine deficiency affects about two billion people and is the leading preventable cause of intellectual disabilities.
Iodine deficiency is a lack of the trace element iodine, an essential nutrient in the diet.

Iodide

II − iodides
Iodine occurs in many oxidation states, including iodide (I − ), iodate, and the various periodate anions.
Compounds with iodine in formal oxidation state −1 are called iodides.

Bernard Courtois

CourtoisB. CourtoisCourtois, Bernard
The element was discovered by the French chemist Bernard Courtois in 1811.
Bernard Courtois, also spelled Barnard Courtois, (8 February 1777 – 27 September 1838) was a French chemist credited with first isolating iodine and morphine.

Iodate

iodatespotassium hydrogen iodateIO 3 −
Iodine occurs in many oxidation states, including iodide (I − ), iodate, and the various periodate anions.
In the iodate anion, iodine is bonded to three oxygen atoms and the molecular formula is.

Bromine

Brbrominatedbromo
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).
Its properties are thus intermediate between those of chlorine and iodine.

Humphry Davy

Sir Humphry DavyDavySir Humphry Davy, Bt
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.
Sir Humphry Davy, 1st Baronet (17 December 1778 – 29 May 1829) was a Cornish chemist and inventor, who is best remembered today for isolating, using electricity, a series of elements for the first time: potassium and sodium in 1807 and calcium, strontium, barium, magnesium and boron the following year, as well as discovering the elemental nature of chlorine and iodine.

Astatine

AtAlabamiumelement 85
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).
Many of them have been estimated based on the element's position on the periodic table as a heavier analog of iodine, and a member of the halogens (the group of elements including fluorine, chlorine, bromine, and iodine).

Triiodide

RbI 3 triiodide (I 3 )triiodide anion
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.
This anion, one of the polyhalogen ions, is composed of three iodine atoms.

Nutrition

nutrition sciencenutritionalnutritional science
Iodine and its compounds are primarily used in nutrition.
In 1896, Eugen Baumann observed iodine in thyroid glands.

Potassium iodide

KISSKIPotassium iodide (KI)
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.
As a supplement it is used in those who have low intake of iodine in the diet.

Isotopes of iodine

radioactive iodineradioiodineiodine-124
Of the thirty-seven known isotopes of iodine, only one occurs in nature, iodine-127.
There are 37 known isotopes of iodine ( 53 I) from 108 I to 144 I; all undergo radioactive decay except 127 I, which is stable.

Radiocontrast agent

radiocontrastcontrastcontrast agent
Due to its high atomic number and ease of attachment to organic compounds, it has also found favour as a non-toxic radiocontrast material.

Chlorine

Clchlorine gaschlorinated
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). 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.
Its properties are thus similar to fluorine, bromine, and iodine, and are largely intermediate between those of the first two.

Iodine-129

129 II-129 129 I
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.
Iodine-129 ( 129 I) is a long-lived radioisotope of iodine which occurs naturally, but also is of special interest in the monitoring and effects of man-made nuclear fission decay products, where it serves as both tracer and potential radiological contaminant.

Iodine-125

125 I125-I125I
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.
Iodine-125 ( 125 I) is a radioisotope of iodine which 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 tumors.

Iodine-123

123 I 123 I iodide 123 iodine
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.
Iodine-123 ( 123 I) is a radioactive isotope of iodine used in nuclear medicine imaging, including single photon emission computed tomography (SPECT) or SPECT/CT exams.

Atomic number

proton numberZatomic numbers
Iodine is a chemical element with the symbol I and atomic number 53.
However, in consideration of the elements' observed chemical properties, he changed the order slightly and placed tellurium (atomic weight 127.6) ahead of iodine (atomic weight 126.9).

Iodine-131

131 II-131radioiodine therapy
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.
Iodine-131 ( 131 I) is an important radioisotope of iodine discovered by Glenn Seaborg and John Livingood in 1938 at the University of California, Berkeley.

Charge-transfer complex

charge transfercharge transfer complexcharge-transfer
Charge-transfer complexes form when iodine is dissolved in polar solvents, hence changing the colour.
A well-known example is the complex formed by iodine when combined with starch, which exhibits an intense blue charge-transfer band.

Symbol (chemistry)

symbolchemical symbolchemical symbols
Iodine is a chemical element with the symbol I and atomic number 53.

Radioactive tracer

radiotracerradiolabeledradiolabel
Iodine-131 is also used as a radioactive tracer.
Radioisotopes of hydrogen, carbon, phosphorus, sulfur, and iodine have been used extensively to trace the path of biochemical reactions.

Diatomic molecule

diatomicdiatomic moleculesdi-
Elemental iodine hence forms diatomic molecules with chemical formula I 2, 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.
At slightly elevated temperatures, the halogens bromine (Br 2 ) and iodine (I 2 ) also form diatomic gases.

Nicolas Clément

Nicolas ClementClément-Desormes
Courtois gave samples to his friends, Charles Bernard Desormes (1777–1838) and Nicolas Clément (1779–1841), to continue research.
They also conducted research on iodine and played a role in determining that it was an element.