NO. 053Halogen

I

Iodine

Iodine is a dark halogen essential for thyroid function and widely used in medicine and disinfectants.

Crystal Structure

Orthorhombic

Atomic Mass126.9 u

Density4.93 g/cm³

Melting Point387 K

Boiling Point457 K

Atomic Radius115 pm

Electronegativity2.66

Ionization Energy1008 kJ/mol

Electron Affinity295 kJ/mol

Bonding TypeCovalent

Oxidation States-1, 1, 5, 7

Acid/BaseAcidic

ReactivityMedium

Electron Configuration

[Kr] 4d10 5s2 5p5

Discovered ByBernard Courtois

Year1811

Known Isotopes

I-127