Iodine (I)

Iodine is a chemical element with symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a lustrous, purple-black nonmetallic solid at standard conditions that melts to form a deep violet liquid at 114 degrees Celsius.

Atomic Number

53

Atomic Mass

126.9 u

Category

halogen

Phase

solid

Density

4.933 g/cm³

Electron Shells

2, 8, 18, 18, 7

Atomic Structure

Protons: 53 • Electrons: 53 • Neutrons: Varies by isotope

Electron Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁵

Discovery

1811 • Bernard Courtois