09-05-2023-2037 - draft (iodine, etc., draft)

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This article is about the chemical element. For other uses, see Iodine (disambiguation).

Iodine, ₅₃I

Iodine
Pronunciation	/ˈaɪədaɪn, -dɪn, -diːn/ ​(EYE-ə-dyne, -⁠din, -⁠deen)
Appearance	lustrous metallic gray solid, black/violet liquid, violet gas
Standard atomic weight Ar°(I)
	126.90447±0.00003 126.90±0.01 (abridged)[1]
Iodine in the periodic table
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 Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver 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 Gold Mercury (element) Thallium Lead 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 Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Br ↑ I ↓ At tellurium ← iodine → xenon
Atomic number (Z)	53
Group	group 17 (halogens)
Period	period 5
Block	p-block
Electron configuration	[Kr] 4d10 5s2 5p5
Electrons per shell	2, 8, 18, 18, 7
Physical properties
Phase at STP	solid
Melting point	(I2) 386.85 K ​(113.7 °C, ​236.66 °F)
Boiling point	(I2) 457.4 K ​(184.3 °C, ​363.7 °F)
Density (near r.t.)	4.933 g/cm3
Triple point	386.65 K, ​12.1 kPa
Critical point	819 K, 11.7 MPa
Heat of fusion	(I2) 15.52 kJ/mol
Heat of vaporisation	(I2) 41.57 kJ/mol
Molar heat capacity	(I2) 54.44 J/(mol·K)
Vapour pressure (rhombic) P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 260 282 309 342 381 457
Atomic properties
Oxidation states	−1, 0, +1, +2,[2] +3, +4, +5, +6, +7 (a strongly acidic oxide)
Electronegativity	Pauling scale: 2.66
Ionisation energies	1st: 1008.4 kJ/mol 2nd: 1845.9 kJ/mol 3rd: 3180 kJ/mol
Atomic radius	empirical: 140 pm
Covalent radius	139±3 pm
Van der Waals radius	198 pm
Spectral lines of iodine
Other properties
Natural occurrence	primordial
Crystal structure	​base-centered orthorhombic
Thermal conductivity	0.449 W/(m⋅K)
Electrical resistivity	1.3×107 Ω⋅m (at 0 °C)
Magnetic ordering	diamagnetic[3]
Molar magnetic susceptibility	−88.7×10−6 cm3/mol (298 K)[4]
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 view talk edit | references

Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions 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 'violet-coloured'.

Iodine occurs in many oxidation states, including iodide (I⁻), iodate (IO⁻
₃), and the various periodate anions. It is the least abundant of the stable halogens, being the sixty-first most abundant element. As the heaviest essential mineral nutrient, iodine is required for the synthesis of thyroid hormones.^[5] Iodine deficiency affects about two billion people and is the leading preventable cause of intellectual disabilities.^[6]

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.^[7] 

https://en.wikipedia.org/wiki/Iodine