Symbol	I
Atomic number	53
Group	17 (Fluorine group)
Period	5
Block	p
Classification	Nonmetal

Appearance	Lustrous metallic gray, violet as a gas
Color	SlateGray

Number of protons	53 p+
Number of neutrons	74 n0
Number of electrons	53 e-

From Wikipedia, the free encyclopediaIodine is a chemical element with symbol I and atomic number 53. The name is from Greek ἰοειδής ioeidēs, meaning violet or purple, due to the color of iodine vapor. Iodine and its compounds are primarily used in nutrition, and industrially in the production of acetic acid and certain polymers.

Phase at STP	Solid
Density	4.933 g/cm3
Atomic weight	126.904 u

Melting point	386.85 K 113.7 °C 236.66 °F
Boiling point	457.4 K 184.25 °C 363.65 °F
Heat of vaporization	20.9 kJ/mol

Electronegativity (Pauling Scale)	2.66
Electron affinity	295.153 kJ/mol
Oxidation states	−1, +1, +3, +4, +5, +6, +7 (a strongly acidic oxide)
Ionization energies	1008.4 kJ/mol 1845.9 kJ/mol 3180 kJ/mol

Electron configuration Shorthand configuration	[Kr] 4d10 5s2 5p5
Electron configuration Full configuration	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p5
Electron configuration chart	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p5
Electrons per shell	2, 8, 18, 18, 7
Valence electrons	7
Valency electrons	1,3,5,7
Bohr model	Figure: Shell diagram of Iodine (I) atom.
Orbital Diagram	1s 2s 2p 3s 3p 3d 4s 4p 4d 5s 5p

Discovery and first isolation	Bernard Courtois (1811)
Named by	Joseph Louis Gay-Lussac (1813)
Discovery of iodine In 1811, iodine was discovered by French chemist Bernard Courtois. He once added excessive sulfuric acid when making Saltpetre and a cloud of purple vapour rose. He noted that the vapour crystallised on cold surfaces, making dark crystals. Courtois suspected that this material was a new element but lacked funding to pursue it further. Courtois gave samples to his friends, Charles Bernard Desormes and Nicolas Clément, to continue research. He also gave some of the substance to chemist Joseph Louis Gay-Lussac, and to physicist André-Marie Ampère. On 29 November 1813, Desormes and Clément made Courtois' discovery public. They described the substance to a meeting of the Imperial Institute of France. On 6 December, Gay-Lussac announced that the new substance was either an element or a compound of oxygen. Gay-Lussac suggested the name "iode", from the Ancient Greek ἰοειδής (ioeidēs, "violet"), because of the colour of iodine vapor. Ampère had given some of his sample to English chemist Humphry Davy, who experimented on the substance and noted its similarity to chlorine. Davy sent a letter dated 10 December to the Royal Society of London stating that he had identified a new element. Arguments erupted between Davy and Gay-Lussac over who identified iodine first, but both scientists acknowledged Courtois as the first to isolate the element.

CAS Number	7553-56-2
ChemSpider ID	4514549
EC number	231-442-4
PubChem CID Number	807