Iodine

Iodine,  ₅₃I

General properties
Name, seembol	iodine, I
Appearance	lustrous metallic gray, violet as a gas
Pronunciation	/ˈaɪ.ədaɪn/ EYE-ə-dyn, /ˈaɪ.ədᵻn/ EYE-ə-dən, or /ˈaɪ.ədiːn/ EYE-ə-deen
Iodine in the periodic cairt
Br ↑ I ↓ At tellurium ← iodine → xenon
Atomic nummer (Z)	53
Group, block	group 17 (halogens), p-block
Period	period 5
Element category	diatomic nonmetal
Staundart atomic wicht (Ar)	126.90447
Electron configuration	[Kr] 4d10 5s2 5p5
per shell	2, 8, 18, 18, 7
Pheesical properties
Phase	solid
Meltin pynt	386.85 K ​(113.7 °C, ​236.66 °F)
Bylin pynt	457.4 K ​(184.3 °C, ​363.7 °F)
Density near r.t.	4.933 g/cm3
Triple pynt	386.65 K, ​12.1 kPa
Creetical pynt	819 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 states	7, 5, 3, 1, -1 (strongly acidic oxide)
Electronegativity	Pauling scale: 2.66
Atomic radius	empirical: 140 pm
Covalent radius	139±3 pm
Van der Waals radius	198 pm
Miscellanea
Crystal structur	​orthorhombic
Thermal conductivity	0.449 W/(m·K)
Electrical resistivity	1.3×107 Ω·m (at 0 °C)
Magnetic orderin	diamagnetic
Bulk modulus	7.7 GPa
CAS Nummer	7553-56-2
History
Discovery	Bernard Courtois (1811)
First isolation	Bernard Courtois (1811)
Maist stable isotopes o iodine
iso NA hauf-life DM DE (MeV) DP 123I syn 13 h ε, γ 0.16 123Te 124I syn 4.176 d ε - 124Te 125I syn 59.40 d ε - 125Te 127I 100% - (SF) <29.961 129I trace 1.57×107 y β− 0.194 129Xe 131I syn 8.02070 d β−, γ 0.971 131Xe 135I syn 6.57 h β− - 135Xe
Decay modes in parentheses are predictit, but hae nae yet been observed

Iodine is a chemical element wi seembol I an atomic nummer 53. The name is frae Greek ἰοειδής ioeidēs, meanin violet or purpie, due tae the colour o elemental iodine vapor.