Iodine Elemental Symbol

French German Italian Portuguese Spanish Swedish
L'iode Jod Iodio Iodo Yodo Jod

Iodine(I) atomic and molecular weight, atomic number and elemental symbol Iodine is a Block P, Group 17, Period 5 element. Elemental IodineThe number of electrons in each of Iodine's shells is 2, 8, 18, 18, 7 and its electron configuration is [Kr] 4d10 5s2 5p5. Iodine Bohr ModelThe iodine atom has a radius of and it's Van der Waals radius is In its elemental form, CAS 7553-56-2, iodine has a lustrous metallic gray appearance as a solid. As a gas it has a violet appearance. Iodine is found mainly as the highly water-soluble iodide I-. Iodine was discovered and first isolated by Bernard Courtois in 1811.

Iodine forms compounds with many elements, but is less active than the other halogens. Iodine is only slightly soluble in water. It dissolves readily in chloroform, carbon tetrachloride, or carbon disulfide to form purple solutions. Iodine compounds are important in organic chemistry and very useful in medicine. Potassium iodide is used in photography. Iodine is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). Elemental or metallic forms include pellets, rod, wire and granules for evaporation source material purposes. Iodine nanoparticles and nanopowders provide ultra-high surface area which nanotechnology research and recent experiments demonstrate function to create new and unique properties and benefits. Oxides are available in powder and dense pellet form for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Fluorides are another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Iodine is also available in soluble forms including chlorides, nitrates and acetates. These compounds can be manufactured as solutions at specified stoichiometries.

Iodine in large amounts is poisonous but in small doses is only slightly toxic. Safety data for Iodine and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab below.

  • Properties
  • Safety Data
  • Products
  • Research
  • Isotopes
  • Other Elements

Iodine Properties

Symbol: I Melting Point: 113.7 oC, 236.66 oF, 386.85 K
Atomic Number: 53 Boiling Point: 184.4 oC, 363.92 oF, 457.55 K
Atomic Weight: 126.9 Density: 4953 kg m-3
Element Category: halogen Liquid Density @ Melting Point: N/A
Group, Period, Block: 17 (halogens), 5, p Specific Heat: N/A
    Heat of Vaporization 41.57 kJ mol-1 of I2
CHEMICAL STRUCTURE Heat of Fusion 15.52 kJ mol-1 of I2
Electrons: 53 Thermal Conductivity: 0.449 W·m−1·K−1
Protons: 53 Thermal Expansion: N/A
Neutrons: 74 Electrical Resistivity: (0 °C) 1.3×107Ω·m
Electron Configuration: [Kr]5s24d105p5 Electronegativity: 2.66 (Pauling scale)
Atomic Radius: 140 pm Tensile Strength: N/A
Covalent Radius: 139±3 pm Molar Heat Capacity: (I2) 54.44 J·mol−1·K−1
Van der Waals radius: 198 pm Young's Modulus: N/A
Oxidation States: 5, 7, -1 Shear Modulus: N/A
Phase: Solid Bulk Modulus: 7.7 GPa
Crystal Structure: orthorhombic Poisson Ratio: N/A
Magnetic Ordering: diamagnetic Mohs Hardness: N/A
1st Ionization Energy: 1008.4 kJ mol-1 Vickers Hardness: N/A
2nd Ionization Energy: 1845.8 kJ mol-1 Brinell Hardness: N/A
3rd Ionization Energy: 3184 kJ mol-1 Speed of Sound: N/A
CAS Number: 7553-56-2 Abundance in typical human body, by weight: 200 ppb
ChemSpider ID: 4514549 Abundance in typical human body, by atom: 10 atoms relative to C = 1000000
PubChem CID: 807 Abundance in universe, by weight: 1 ppb
MDL Number: MFCD00011355 Abundance in universe, by atom: 0.01 ppb
EC Number: 231-442-4 Discovered By: Bernard Courtois
Beilstein Number: 3587194 Discovery Date: 1811
SMILES Identifier: [I]  
InChI Identifier: InChI=1S/I Other Names: Jod, Iodio

Iodine Products

Recent Research & Development for Iodine

  • Spectrophotometric investigation of interaction between iodine and pentadentate Schiff base ligands. Khouba Z, Benabdallah T, Maschke U. Spectrochim Acta A Mol Biomol Spectrosc. 2014.
  • Silver oxide nanocrystals anchored on titanate nanotubes and nanofibers: promising candidates for entrapment of radioactive iodine anions. Nanoscale. | first author:Yang D.
  • Influence of lake trophic structure on iodine-131 accumulation and subsequent cumulative radiation dose to trout thyroids. Martinez NE, Johnson TE, Pinder JE 3rd. J Environ Radioact. 2014.
  • Halocarbocyclization versus dihalogenation: substituent directed iodine(iii) catalyzed halogenations. Stodulski M, Goetzinger A, Kohlhepp SV, Gulder T. Chem Commun (Camb). 2014.
  • Radioactive iodine remnant uptake after completion thyroidectomy: not such a complete cancer operation. Oltmann SC, Schneider DF, Leverson G, Sivashanmugam T, Chen H, Sippel RS. Ann Surg Oncol. 2014 Apr.
  • Effect of radioactive iodine therapy on lacrimal gland functions in patients with hyperthyroidism. Aydogan F, Ayhan Tuzcu E, Aydogan A, Akkucuk S, Coskun M, Ustun I, Gökçe C. Clin Nucl Med. 2014.
  • A 3.5 v lithium-iodine hybrid redox battery with vertically aligned carbon nanotube current collector. Zhao Y, Hong M, Bonnet Mercier N, Yu G, Choi HC, Byon HR. Nano Lett. 2014
  • Can low-dose CT with iterative reconstruction reduce both the radiation dose and the amount of iodine contrast medium in a dynamic CT study of the liver? Takahashi H, Okada M, Hyodo T, Hidaka S, Kagawa Y, Matsuki M, Tsurusaki M, Murakami T. Eur J Radiol. 2014
  • Abatement of xenon and iodine emissions from medical isotope production facilities. Doll CG, Sorensen CM, Bowyer TW, Friese JI, Hayes JC, Hoffmann E, Kephart R. J Environ Radioact. 2014
  • Innovative use of povidone-iodine to guide burn wound debridement and predict the success of biobrane as a definitive treatment for burns. Lau YS, Brooks P. Adv Skin Wound Care. 2014
  • Povidone-iodine for endophthalmitis prophylaxis. Ahmed Y, Scott IU, Pathengay A, Bawdekar A, Flynn HW Jr. Am J Ophthalmol 2014.
  • Oxidative stress increased in pregnant women with iodine deficiency. Vidal ZE, Rufino SC, Tlaxcalteco EH, Trejo CH, Campos RM, Meza MN, Rodríguez RC, Arroyo-Helguera O. Biol Trace Elem Res. 2014
  • Immobilization of radioactive iodine in silver aluminophosphate glasses. Lemesle T, Méar FO, Campayo L, Pinet O, Revel B, Montagne L. J Hazard Mater. 2014
  • Mild iodine deficiency in women after spontaneous abortions living in an iodine-sufficient area of Czech Republic: prevalence and impact on reproductive health. Jiskra J, Fait T, Bílek R, Krátký J, Bartáková J, Lukáš J, Límanová Z, Telička Z, Zamrazil V, Potluková E. Clin Endocrinol (Oxf). 2014
  • Erratum to: Iodine status in Korean preschool children as determined by urinary iodine excretion. Lee J, Kim JH, Lee SY, Lee JH. Eur J Nutr. 2014
  • Influencing factors on iodine content of cow milk. Flachowsky G, Franke K, Meyer U, Leiterer M, Schöne F. Eur J Nutr. 2014.
  • Recommended number of participants in iodine nutrition studies is similar before and after an iodine fortification programme. Karmisholt J, Laurberg P, Andersen S. Eur J Nutr. 2014.
  • Comparison of dual-energy CT-derived iodine content and iodine overlay of normal, inflammatory and metastatic squamous cell carcinoma cervical lymph nodes. Tawfik AM, Razek AA, Kerl JM, Nour-Eldin NE, Bauer R, Vogl TJ. Eur Radiol. 2014
  • Seasonal shifts in bacteria associated with Jersey cows on a small dairy farm and the potential for bedding choice and low levels of iodine use to inhibit mastitic pathogens. Waltemyer JR, Hennings R, Hoostal MJ. Prev Vet Med. 2014
  • Iodine-catalyzed three-component oxysulfenylation of alkenes with sulfonyl hydrazides and alcohols. Yang FL, Wang FX, Wang TT, Wang YJ, Tian SK. Chem Commun (Camb). 2014.

Iodine Isotopes

Iodine has one stable isotope: 127I.

Nuclide Symbol Isotopic Mass Half-Life Nuclear Spin
127I 126.904473 Stable 5/2+