Halogen

Iodine

Iodine (I) has atomic number 53. PubChem classifies it as halogen.

Atomic number

53

Symbol

I

Atomic weight (source value)

126.9045

Electron configuration

[Kr]5s2 4d10 5p5

Standard state

Solid

Electronegativity (Pauling)

2.66

Melting point (K)

386.85

Boiling point (K)

457.55

Density (g/cm³)

4.93

Oxidation states

+7, +5, +1, -1

Understanding this entry

Atomic number is the number of protons in the nucleus. Properties are reference values and may depend on conditions and measurement conventions. An atomic weight is not the mass of every isotope. For elements without a standard atomic weight, a source may report an isotope mass number. Blank source values are shown as unavailable rather than estimated.

Further reading and reference: NIH PubChem source dataset ↗. Values and educational summaries are not a substitute for specialised advice.