Atomic number 53
Iodine
Halogen
In the real world
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
[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 dangerous is it?
A purple-black solid that turns straight into a stinging purple vapor. The vapor and the solid irritate eyes, skin, and lungs, so it is used in a fume hood. The iodide in your diet is a completely different, harmless thing.
- CorrosiveImmediate
The purple vapor it gives off stings the eyes and lungs, and the solid stains and burns skin on contact. (the irritating vapor comes from the solid element; dietary iodide is harmless)
Used in a fume hood with gloves and eye protection so the vapor is not breathed.
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.
