a = 725.79 pm b = 478.28 pm c = 982.38 pm (at 20 °C)[3]
Thermal expansion
74.9×10−6/K (at 20 °C)[a]
Thermal conductivity
0.449 W/(m⋅K)
Electrical resistivity
1.3×107 Ω⋅m (at 0 °C)
Magnetic ordering
diamagnetic[5]
Molar magnetic susceptibility
−88.7×10−6 cm3/mol (298 K)[6]
Bulk modulus
7.7 GPa
CAS Number
7553-56-2
History
Discovery and first isolation
Bernard Courtois (1811)
Isotopes of iodine
v
e
Main isotopes
Decay
abundance
half-life (t1/2)
mode
product
123I
synth
13 h
β+100%
123Te
124I
synth
4.176 d
ε
124Te
125I
synth
59.40 d
ε
125Te
127I
100%
stable
129I
trace
1.57×107 y
β−
129Xe
131I
synth
8.02070 d
β−100%
131Xe
135I
synth
6.57 h
β−
135Xe
Category: Iodine
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Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at 114 °C (237 °F), and boils to a violet gas at 184 °C (363 °F). The element was discovered by the French chemist Bernard Courtois in 1811 and was named two years later by Joseph Louis Gay-Lussac, after the Ancient Greek Ιώδης, meaning 'violet'.
Iodine occurs in many oxidation states, including iodide (I−), iodate (IO− 3), and the various periodate anions. As the heaviest essential mineral nutrient, iodine is required for the synthesis of thyroid hormones.[7] Iodine deficiency affects about two billion people and is the leading preventable cause of intellectual disabilities.[8]
The dominant producers of iodine today are Chile and Japan. Due to its high atomic number and ease of attachment to organic compounds, it has also found favour as a non-toxic radiocontrast material. Because of the specificity of its uptake by the human body, radioactive isotopes of iodine can also be used to treat thyroid cancer. Iodine is also used as a catalyst in the industrial production of acetic acid and some polymers.
It is on the World Health Organization's List of Essential Medicines.[9]
^"Standard Atomic Weights: Iodine". CIAAW. 1985.
^Prohaska T, Irrgeher J, Benefield J, Böhlke JK, Chesson LA, Coplen TB, et al. (4 May 2022). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
^ abcArblaster JW (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
^I(II) is known to exist in monoxide (IO); see Nikitin IV (31 August 2008). "Halogen monoxides". Russian Chemical Reviews. 77 (8): 739–749. Bibcode:2008RuCRv..77..739N. doi:10.1070/RC2008v077n08ABEH003788. S2CID 250898175.
^Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.
^Weast R (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
^"Iodine". Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis. 2015. Archived from the original on 17 April 2015. Retrieved 20 November 2017.
^McNeil Jr DG (16 December 2006). "In Raising the World's I.Q., the Secret's in the Salt". The New York Times. Archived from the original on 12 July 2010. Retrieved 21 July 2009.
^World Health Organization (2021). World Health Organization model list of essential medicines: 22nd list (2021). Geneva: World Health Organization. hdl:10665/345533. WHO/MHP/HPS/EML/2021.02.
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Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous...
are 37 known isotopes of iodine (53I) from 108I to 144I; all undergo radioactive decay except 127I, which is stable. Iodine is thus a monoisotopic element...
Iodine deficiency is a lack of the trace element iodine, an essential nutrient in the diet. It may result in metabolic problems such as goiter, sometimes...
Landolt in 1886. The iodine clock reaction exists in several variations, which each involve iodine species (iodide ion, free iodine, or iodate ion) and...
hormones: the most common cause is iodine deficiency. In iodine-deficient regions, hypothyroidism secondary to iodine deficiency is the leading cause of...
phycomycosis. It is a supplement used by people with low dietary intake of iodine. It is administered orally. Common side effects include vomiting, diarrhea...
Tincture of iodine, iodine tincture, or weak iodine solution is an antiseptic. It is usually 2 to 3% elemental iodine, along with potassium iodide or...
Iodine chloride may refer to: Iodine monochloride, ICl Iodine dichloride, ICl2− Iodine trichloride, ICl3 This set index article lists chemical compounds...
In chemistry, the iodine value (IV; also iodine absorption value, iodine number or iodine index) is the mass of iodine in grams that is consumed by 100 grams...
periodic table as a heavier analog of fluorine, chlorine, bromine, and iodine, the four stable halogens. However, astatine also falls roughly along the...
amount of various salts of the element iodine. The ingestion of iodine prevents iodine deficiency. Worldwide, iodine deficiency affects about two billion...
intellectual development in the baby or congenital iodine deficiency syndrome. Worldwide, too little iodine in the diet is the most common cause of hypothyroidism...
chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and the radioactive elements astatine (At) and tennessine (Ts), though...
functioning properly. Worldwide, over 90% of goitre cases are caused by iodine deficiency. The term is from the Latin gutturia, meaning throat. Most goitres...
loud, sharp snap when touched even lightly, releasing a purple cloud of iodine vapor; it can even be detonated by alpha radiation. NI3 has a complex structural...
Iodine trichloride is an interhalogen compound of iodine and chlorine. It is bright yellow but upon time and exposure to light it turns red due to the...
glands, iodine in the form of iodide is selectively gathered into the colloid of the thyroud. Inside the colloid, iodide is reduced to elemental iodine (I2)...
Hydrazone iodination is an organic reaction in which a hydrazone is converted into a vinyl iodide by reaction of iodine and a non-nucleophilic base such...
Iodine is an essential trace element in biological systems. It has the distinction of being the heaviest element commonly needed by living organisms as...
multinodular goiter, toxic adenoma, inflammation of the thyroid, eating too much iodine, and too much synthetic thyroid hormone. A less common cause is a pituitary...
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