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Chlorine

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

Original source

Chlorine (Cl) is chemical element 17, a halogen in group 17, period 3 (PubChem).

  • Atomic number: 17
  • Symbol: Cl
  • Group: 17
  • Period: 3
  • Atomic mass: 35.45 u
  • Electron configuration: [Ne]3s2 3p5
  • Electronegativity (Pauling scale): 3.16
  • Atomic radius (van der Waals): 175 pm
  • Ionization energy: 12.968 eV
  • Electron affinity: 3.617 eV
  • Oxidation states: +7, +5, +1, -1
  • Standard state: Gas
  • Melting point: 171.65 K
  • Boiling point: 239.11 K
  • Density: 0.003214 g/cm³
  • Chemical group: Halogen
  • Year discovered: 1774

Source and provenance

Original source
pubchem.ncbi.nlm.nih.gov
Published on Koskamo by
Koskamo
Citation version
Document v1
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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

  1. Published by Koskamo

    Version 1