Atomic number 53
Iodine
Halogen
Quick facts
- Atomic mass
- 126.90
- Group
- 17
- Period
- 5
- State (STP)
- solid
- Electronegativity
- 2.66
- Common ox. states
- -1, +1, +3, +5, +7
Properties
Electron configuration
[Kr] 4d¹⁰ 5s² 5p⁵
- Ionization energy
- 1008.4 kJ/mol
- Electron affinity
- 295.2 kJ/mol
- Melting point
- 386.85 K (113.7 °C)
- Boiling point
- 457.40 K (184.3 °C)
How it bonds
Iodine forms one bond — I⁻ in NaI, single-bonded in HI, CHI₃, etc. Three lone pairs. The least electronegative stable halogen, so it is the most willing to swing positive (IO₃⁻, IO₄⁻). Sublimes from a violet-black solid to a purple gas, the textbook example of sublimation.