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Compare Chlorine vs Fluorine

Comparing Chlorine (Cl) and Fluorine (F). Atomic numbers 17 and 9 with atomic masses 35.446 u and 18.998 u, classified as nonmetal and nonmetal. Below: a side-by-side comparison of their physical, atomic, electron-configuration and historical properties, including density, melting and boiling points, ionization energies, oxidation states and discovery history.

vs
Cl
Chlorine
#17
F
Fluorine
#9

Periodic properties of the elements

ChlorineFluorine
SymbolClF
Atomic number179
Group1717
Period32
Blockpp
Element categoryNonmetalNonmetal

Physical properties

ChlorineFluorine
Phase at STPGasGas
Density3.2 g/cm31.696 g/cm3
Atomic weight35.446 u18.9984 u
Melting point171.6 K
-101.55 °C
-150.79 °F		53.48 K
-219.67 °C
-363.406 °F
Boiling point239.11 K
-34.04 °C
-29.272 °F		85.03 K
-188.12 °C
-306.616 °F

Atomic properties

ChlorineFluorine
Electronegativity (Pauling Scale)3.163.98
Electron affinity348.575 kJ/mol328.165 kJ/mol
Oxidation states−1, +1, +2, +3, +4, +5, +6, +7
(a strongly acidic oxide)		−1, 0
(oxidizes oxygen)
Ionization energies
  1. 1251.2 kJ/mol
  2. 2298 kJ/mol
  3. 3822 kJ/mol
  4. 5158.6 kJ/mol
  5. 6542 kJ/mol
  6. 9362 kJ/mol
  7. 11018 kJ/mol
  8. 33604 kJ/mol
  9. 38600 kJ/mol
  10. 43961 kJ/mol
  11. 51068 kJ/mol
  12. 57119 kJ/mol
  13. 63363 kJ/mol
  14. 72341 kJ/mol
  15. 78095 kJ/mol
  16. 352994 kJ/mol
  17. 380760 kJ/mol
  1. 1681 kJ/mol
  2. 3374.2 kJ/mol
  3. 6050.4 kJ/mol
  4. 8407.7 kJ/mol
  5. 11022.7 kJ/mol
  6. 15164.1 kJ/mol
  7. 17868 kJ/mol
  8. 92038.1 kJ/mol
  9. 106434.3 kJ/mol

Electron configuration

ChlorineFluorine
Shorthand configuration[Ne] 3s2 3p5 [He] 2s2 2p5
Full configuration1s2 2s2 2p6 3s2 3p5 1s2 2s2 2p5
Electrons per shell2, 8, 72, 7

History

ChlorineFluorine
DiscoveryCarl Wilhelm Scheele (1774)André-Marie Ampère (1810)
First isolationCarl Wilhelm Scheele (1774)Henri Moissan (1886)
Named bySir Humphry Davy (1810)Humphry Davy, André-Marie Ampère
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