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Compare Sodium vs Potassium

Comparing Sodium (Na) and Potassium (K). Atomic numbers 11 and 19 with atomic masses 22.99 u and 39.098 u, classified as alkali metal and alkali metal. 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
Na
Sodium
#11
K
Potassium
#19

Periodic properties of the elements

SodiumPotassium
SymbolNaK
Atomic number1119
Group11
Period34
Blockss
Element categoryAlkali MetalAlkali Metal

Physical properties

SodiumPotassium
Phase at STPSolidSolid
Density0.968 g/cm30.862 g/cm3
Atomic weight22.9898 u39.0983 u
Melting point370.944 K
97.794 °C
208.0292 °F		336.7 K
63.55 °C
146.39 °F
Boiling point1156.09 K
882.94 °C
1621.292 °F		1032 K
758.85 °C
1397.93 °F

Atomic properties

SodiumPotassium
Electronegativity (Pauling Scale)0.930.82
Electron affinity52.867 kJ/mol48.383 kJ/mol
Oxidation states−1, +1
(a strongly basic oxide)		−1, +1
(a strongly basic oxide)
Ionization energies
  1. 495.8 kJ/mol
  2. 4562 kJ/mol
  3. 6910.3 kJ/mol
  4. 9543 kJ/mol
  5. 13354 kJ/mol
  6. 16613 kJ/mol
  7. 20117 kJ/mol
  8. 25496 kJ/mol
  9. 28932 kJ/mol
  10. 141362 kJ/mol
  11. 159076 kJ/mol
  1. 418.8 kJ/mol
  2. 3052 kJ/mol
  3. 4420 kJ/mol
  4. 5877 kJ/mol
  5. 7975 kJ/mol
  6. 9590 kJ/mol
  7. 11343 kJ/mol
  8. 14944 kJ/mol
  9. 16963.7 kJ/mol
  10. 48610 kJ/mol
  11. 54490 kJ/mol
  12. 60730 kJ/mol
  13. 68950 kJ/mol
  14. 75900 kJ/mol
  15. 83080 kJ/mol
  16. 93400 kJ/mol
  17. 99710 kJ/mol
  18. 444880 kJ/mol
  19. 476063 kJ/mol

Electron configuration

SodiumPotassium
Shorthand configuration[Ne] 3s1 [Ar] 4s1
Full configuration1s2 2s2 2p6 3s1 1s2 2s2 2p6 3s2 3p6 4s1
Electrons per shell2, 8, 12, 8, 8, 1

History

SodiumPotassium
DiscoveryHumphry Davy (1807)Humphry Davy (1807)
First isolationHumphry Davy (1807)Humphry Davy (1807)
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