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Iodine is a chemical element wi seembol I an atomic nummer 53. The hiviest o the stable halogens, it exeests as a lustrous, purpie-black nan-metallic solit at staundart condeetions that sublimes readily tae form a violet gas. The elemental form wis diskivert bi the French chemist Bernard Courtois in 1811. It wis named twa years later bi Joseph Louis Gay-Lussac frae this property, efter the Greek ἰώδης "violet-coloured".

Iodine,  53I
Sample of iodine.jpg
General properties
Appearancelustrous metallic gray, violet as a gas
Staundart atomic wecht (Ar, staundart)126.90447(3)[1]
Iodine in the periodic cairt
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Airn Cobalt Nickel Capper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Siller (element) Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gowd Mercur (element) Thallium Leid (element) Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Ununtrium Flerovium Ununpentium Livermorium Ununseptium Ununoctium
Br

I

At
telluriumiodinexenon
Atomic nummer (Z)53
Groupgroup 17 (halogens)
Periodperiod 5
Element category  diatomic nonmetal
Blockp-block
Electron confeeguration[Kr] 4d10 5s2 5p5
Electrons per shell
2, 8, 18, 18, 7
Pheesical properties
Phase (at STP)solit
Meltin pynt386.85 K ​(113.7 °C, ​236.66 °F)
Bylin pynt457.4 K ​(184.3 °C, ​363.7 °F)
Density (near r.t.)4.933 g/cm3
Treeple pynt386.65 K, ​12.1 kPa
Creetical pynt819 K, 11.7 MPa
Heat o fusion(I2) 15.52 kJ/mol
Heat o vapourisation(I2) 41.57 kJ/mol
Molar heat capacity(I2) 54.44 J/(mol·K)
Vapour pressur (rhombic)
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 260 282 309 342 381 457
Atomic properties
Oxidation states7, 5, 3, 1, -1
(strongly acidic oxide)
ElectronegativityPauling scale: 2.66
Atomic radiusempirical: 140 pm
Covalent radius139±3 pm
Van der Waals radius198 pm
Coloyr lines in a spectral range
Spectral lines o Iodine
Miscellanea
Creestal structurorthorhombic
Orthorhombic creestal structur for iodine
Thermal conductivity0.449 W/(m·K)
Electrical resistivity1.3×107 Ω·m (at 0 °C)
Magnetic orderindiamagnetic[2]
Bouk modulus7.7 GPa
CAS Nummer7553-56-2
History
DiskiveryBernard Courtois (1811)
First isolationBernard Courtois (1811)
Main isotopes o iodine
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct
123I syn 13 h ε, γ 123Te
124I syn 4.176 d ε 124Te
125I syn 59.40 d ε 125Te
127I 100% - (SF)
129I trace 1.57×107 y β 129Xe
131I syn 8.02070 d β, γ 131Xe
135I syn 6.57 h β 135Xe
Decay modes in parentheses are predictit, but hae nae yet been observed
| references | in Wikidata

Iodine occurs in mony oxidation states, includin iodide (I), iodate (IO
3
), an the various periodate anions. It is the least abundant o the stable halogens, bein the saxty-first maist abundant element. It is even less abundant nor the sae-cried rare yirds. It is the hiviest essential mineral nutrient. Iodine is essential in the synthesis o thyroid hormones.[3] Iodine deficiency affects aboot twa billion fowk an is the leadin preventable cause o intellectual disabilities.

The dominant producers o iodine the day are Chile an Japan. Iodine an its compoonds are primarily uised in nutreetion. Due tae its heich atomic nummer an ease o attachment tae organic compoonds, it haes an aw found favour as a nan-toxic radiocontrast material. Acause o the speceeficity o its uptak bi the human bouk, radioactive isotopes o iodine can an aw be uised tae treat thyroid cancer. Iodine is an aw uised as a catalyst in the industrial production o acetic acid an some polymers.

ReferencesEedit

  1. Meija, J.; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305. 
  2. Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.
  3. "Iodine". Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis, OR. 2015. Retrieved 20 November 2017.