53 I 126.904

Iodine

diatomic nonmetal

Properties

Atomic number
53
Atomic mass
126.904 u
Category
diatomic nonmetal
Group
17
Period
5
Block
p-block
State (room temp)
Solid
Outer-shell electrons
7
Electronegativity
2.66 (Pauling)
Density
4.933 g/cm³
Melting point
113.7 °C
Boiling point
184.25 °C

Electron configuration

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁵

Noble-gas shorthand: [Kr] 4d¹⁰ 5s² 5p⁵

Electrons per shell: 2, 8, 18, 18, 7 — that's 7 in the outermost shell.

See how electron configuration is built →

I
Bohr model — outer-shell electrons in blue

About Iodine

Iodine is a chemical element with symbol I and atomic number 53. The name is from Greek ἰοειδής ioeidēs, meaning violet or purple, due to the color of iodine vapor. Iodine and its compounds are primarily used in nutrition, and industrially in the production of acetic acid and certain polymers.

Position in the periodic table

Open the interactive periodic table →

Data compiled from Wikipedia, PubChem, and IUPAC. Source.