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Compare Calcium vs Magnesium

Comparing Calcium (Ca) and Magnesium (Mg). Atomic numbers 20 and 12 with atomic masses 40.078 u and 24.304 u, classified as alkaline earth metal and alkaline earth 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
Ca
Calcium
#20
Mg
Magnesium
#12

Periodic properties of the elements

CalciumMagnesium
SymbolCaMg
Atomic number2012
Group22
Period43
Blockds
Element categoryAlkaline Earth MetalAlkaline Earth Metal

Physical properties

CalciumMagnesium
Phase at STPSolidSolid
Density1.55 g/cm31.738 g/cm3
Atomic weight40.0784 u24.304 u
Melting point1115 K
841.85 °C
1547.33 °F		923 K
649.85 °C
1201.73 °F
Boiling point1757 K
1483.85 °C
2702.93 °F		1363 K
1089.85 °C
1993.73 °F

Atomic properties

CalciumMagnesium
Electronegativity (Pauling Scale)11.31
Electron affinity2.37 kJ/mol-40 kJ/mol
Oxidation states+1, +2
(a strongly basic oxide)		+1, +2
(a strongly basic oxide)
Ionization energies
  1. 589.8 kJ/mol
  2. 1145.4 kJ/mol
  3. 4912.4 kJ/mol
  4. 6491 kJ/mol
  5. 8153 kJ/mol
  6. 10496 kJ/mol
  7. 12270 kJ/mol
  8. 14206 kJ/mol
  9. 18191 kJ/mol
  10. 20385 kJ/mol
  11. 57110 kJ/mol
  12. 63410 kJ/mol
  13. 70110 kJ/mol
  14. 78890 kJ/mol
  15. 86310 kJ/mol
  16. 94000 kJ/mol
  17. 104900 kJ/mol
  18. 111711 kJ/mol
  19. 494850 kJ/mol
  20. 527762 kJ/mol
  1. 737.7 kJ/mol
  2. 1450.7 kJ/mol
  3. 7732.7 kJ/mol
  4. 10542.5 kJ/mol
  5. 13630 kJ/mol
  6. 18020 kJ/mol
  7. 21711 kJ/mol
  8. 25661 kJ/mol
  9. 31653 kJ/mol
  10. 35458 kJ/mol
  11. 169988 kJ/mol
  12. 189368 kJ/mol

Electron configuration

CalciumMagnesium
Shorthand configuration[Ar] 4s2 [Ne] 3s2
Full configuration1s2 2s2 2p6 3s2 3p6 4s2 1s2 2s2 2p6 3s2
Electrons per shell2, 8, 8, 22, 8, 2

History

CalciumMagnesium
DiscoveryHumphry Davy (1808)Joseph Black (1755)
First isolationHumphry Davy (1808)Humphry Davy (1808)
Named byHumphry Davy (1812)
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