• The?strength?of electrostatic attraction can be increased by:
  • Increasing?the number of?delocalised?electrons?per metal atom
  • Increasing?the?positive?charges?on the metal centres in the lattice
  • Decreasing?the?size?of the metal ions
• These factors can be seen in the trends across a period and down a group

Melting points of metals across a period

• If you compare the electron configuration of sodium, magnesium and aluminium you can see the number of valence electrons increases
  • Na = 1s²2s²2p⁶3s¹
  • Mg = 1s²2s²2p⁶3s²
  • Al? = 1s²2s²2p⁶3s²3p¹?
• Aluminium ions are also a smaller size?than magnesium ions or sodium ions and these two factors lead to?stronger?metallic bonding which can be seen in the melting points
• The?stronger?the metallic bonding, the?more energy?is need to break the metallic lattice and so the?higher?the melting point
• As we go across period 3 we can see the effect of stronger metallic bonding on the metals
  • Remember only the first three elements have metallic bonding in this graph

Melting points as you go across a period. The metallic bonding gets stronger from Na to Al

Melting points of metals down a group

• As you go?down the group?the size of the cation increases so this?decreases the attraction?between the valence electrons and the metallic lattice, leading to a reduction of the melting point

Melting points as you go down a group of metals. The metallic bonding gets weaker from Li to Cs