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Compare Aluminium vs Silicon

Comparing Aluminium (Al) and Silicon (Si). Atomic numbers 13 and 14 with atomic masses 26.982 u and 28.084 u, classified as post-transition metal and metalloid. 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.

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Periodic properties of the elements

AluminiumSilicon
SymbolAlSi
Atomic number1314
Group1314
Period33
Blockpp
Element categoryPost-Transition MetalMetalloid

Physical properties

AluminiumSilicon
Phase at STPSolidSolid
Density2.7 g/cm32.329 g/cm3
Atomic weight26.9815 u28.084 u
Melting point933.47 K
660.32 °C
1220.576 °F
1687 K
1413.85 °C
2576.93 °F
Boiling point2743 K
2469.85 °C
4477.73 °F
3538 K
3264.85 °C
5908.73 °F

Atomic properties

AluminiumSilicon
Electronegativity (Pauling Scale)1.611.9
Electron affinity41.762 kJ/mol134.068 kJ/mol
Oxidation states−2, −1, +1, +2, +3
(an amphoteric oxide)
−4, −3, −2, −1, 0, +1, +2, +3, +4
(an amphoteric oxide)
Ionization energies
  1. 577.5 kJ/mol
  2. 1816.7 kJ/mol
  3. 2744.8 kJ/mol
  4. 11577 kJ/mol
  5. 14842 kJ/mol
  6. 18379 kJ/mol
  7. 23326 kJ/mol
  8. 27465 kJ/mol
  9. 31853 kJ/mol
  10. 38473 kJ/mol
  11. 42647 kJ/mol
  12. 201266 kJ/mol
  13. 222316 kJ/mol
  1. 786.5 kJ/mol
  2. 1577.1 kJ/mol
  3. 3231.6 kJ/mol
  4. 4355.5 kJ/mol
  5. 16091 kJ/mol
  6. 19805 kJ/mol
  7. 23780 kJ/mol
  8. 29287 kJ/mol
  9. 33878 kJ/mol
  10. 38726 kJ/mol
  11. 45962 kJ/mol
  12. 50502 kJ/mol
  13. 235196 kJ/mol
  14. 257923 kJ/mol

Electron configuration

AluminiumSilicon
Shorthand configuration[Ne] 3s2 3p1 [Ne] 3s2 3p2
Full configuration1s2 2s2 2p6 3s2 3p1 1s2 2s2 2p6 3s2 3p2
Electrons per shell2, 8, 32, 8, 4

History

AluminiumSilicon
PredictionAntoine Lavoisier (1782)Antoine Lavoisier (1787)
DiscoveryHans Christian Ørsted (1824)Jöns Jacob Berzelius (1823)
First isolationJöns Jacob Berzelius (1823)
Named byHumphry Davy (1812)Thomas Thomson (1817)