iodine

Also known as I, element 53, ₅₃I

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 , and boils to a violet gas at . 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 , meaning 'violet'.

AI overview

Iodine is a chemical element (symbol I, atomic number 53) that appears as a dark, shiny solid at room temperature and turns into a deep violet liquid or gas when heated. It was discovered in 1811 by French chemist Bernard Courtois and named for its distinctive violet color, which comes from the Ancient Greek word for "violet."

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Key facts

Iodine.engvar: en-GB

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Research

151,682 papers

Iodine(III) reagents for oxidative aromatic halogenation.ReviewOrganic & biomolecular chemistry · 2022Segura-Quezada LA, Torres-Carbajal KR, Juárez-Ornelas KA et al.DOI: 10.1039/d2ob00741j
Iodine deficiency disorders in Europe.ReviewBulletin of the World Health Organization · 1989Delange F, Bürgi H
The Iodine Rush: Over- or Under-Iodination Risk in the Prophylactic Use of Iodine for Thyroid Blocking in the Event of a Nuclear Disaster.ReviewFrontiers in endocrinology · 2022Calcaterra V, Mameli C, Rossi V et al.DOI: 10.3389/fendo.2022.901620
Iodine Species Quantification and Transformation during Chlorination in the Presence of Ammonia.Environmental science & technology · 2025Xu S, Liu R, Zhao L et al.DOI: 10.1021/acs.est.5c06645
Iodine(III)-Mediated Fluorination/Semipinacol Rearrangement Cascade of 2-Alkylidenecyclobutanol Derivatives: Access to β-Monofluorinated Cyclopropanecarbaldehydes.The Journal of organic chemistry · 2021Feng SX, Yang S, Tu FH et al.DOI: 10.1021/acs.joc.1c00578
Standard Radio-Iodine Labeling Protocols Impaired the Functional Integrity of Mesenchymal Stem/Stromal Cell Exosomes.International journal of molecular sciences · 2024Yang CT, Lai RC, Phua VJX et al.DOI: 10.3390/ijms25073742
Iodine derivatives of chemically modified gum Arabic microspheres.Carbohydrate polymers · 2015Ganie SA, Ali A, Mazumdar NDOI: 10.1016/j.carbpol.2015.04.044
Occurrence of Iodophenols in Aquatic Environments and the Deiodination of Organic Iodine with Ferrate(VI).Environmental science & technology · 2022Wang XS, Liu YL, Li M et al.DOI: 10.1021/acs.est.2c00857

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Wikidata facts

Mass: 126.90447
Image: Iodine'.JPG

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electron configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁵
element symbol: I
Commons category: Iodine
atomic number: 53
time of discovery or invention: 1811-01-01
Commons gallery: Iodine
ionization energy: 9.40
electronegativity: 3
Unicode character: 碘
melting point: 113.7
ionic radius: 0.53
boiling point: 184.4
electric dipole moment: 0

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Article

33 sections

Contents

History
Properties
Isotopes
Chemistry and compounds
Charge-transfer complexes
Hydrogen iodide
Other binary iodine compounds
Iodine halides
Iodine oxides and oxoacids
Polyiodine compounds
Organoiodine compounds
Occurrence and production
Applications
X-ray imaging
Biocide
Optical polarising films
Co-catalyst
Nutrition
Others
Spectroscopy
Chemical analysis
Biological role
Dietary recommendations and intake
Deficiency
Precautions
Toxicity
Occupational exposure
Reaction to iodinated contrast media
US DEA List I status
Notes
References
Bibliography
External links

Iodine occurs in many oxidation states, including iodide (I−), iodate (), and the various periodate anions. As the heaviest essential mineral nutrient, iodine is required for the synthesis of thyroid hormones. Iodine deficiency affects about two billion people and is the leading preventable cause of intellectual disabilities.