Iodine

Document v1 · published by Koskamo · updated 2026-10-04

Iodine (I) is chemical element 53, a halogen in group 17, period 5 (PubChem).

Atomic number: 53
Symbol: I
Group: 17
Period: 5
Atomic mass: 126.9045 u
Electron configuration: [Kr]5s2 4d10 5p5
Electronegativity (Pauling scale): 2.66
Atomic radius (van der Waals): 198 pm
Ionization energy: 10.451 eV
Electron affinity: 3.059 eV
Oxidation states: +7, +5, +1, -1
Standard state: Solid
Melting point: 386.85 K
Boiling point: 457.55 K
Density: 4.93 g/cm³
Chemical group: Halogen
Year discovered: 1811

Source and provenance

Original source: pubchem.ncbi.nlm.nih.gov
Published on Koskamo by: Koskamo
Citation version: Document v1
Reuse: PubChem periodic table data (NIH/NLM, pubchem.ncbi.nlm.nih.gov/ptable); group and period from Jefferson Lab via PubChem

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Version history

Published by Koskamo2026-10-04
Version 1