4.5 Metallic bonding

Metallic Bonding

  • Metals have low ionization energies, so valence electrons can be delocalized throughout metal.
  • Structure of metal is a giant lattice of positive ions (cations) surrounded by “sea” of delocalized electrons
  • Metallic Bond: the electrostatic attraction between a lattice of positive ions (cations) and delocalized electrons
  • Strength of metallic bond depends on
    • Number of valence electrons that can become delocalized
    • The charge of the metal ion
    • The ionic radius of the metallic positive ion (cation)

Alloys

  • Alloy is a mixture that consists either of
    • Two or more metals
    • Metal(s) combined with an alloying element (one or more non-metals)
  • Alloys have enhanced properties such as strength, hardness and durability

Electrical Conductivity

  • Metals are good conductors because the delocalized electrons can move through the metallic structure and carry a current
  • Presence of impurities can restrict movement

Malleability

  • Metals are malleable because cations can slide past each other which leads to rearrangement of solid (Non-directional bonding)

Trends in melting points

  • Melting point depends on the strength of the attractive forces that hold the delocalized electron together

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