Question

Answer the following, giving a full explanation in terms of metallic bonding:
Explain why aluminium has a higher melting point than sodium.

Accepted Answer

Aluminium has a higher melting point than sodium because aluminium has a stronger metallic bond compared to sodium. It takes a lot more energy in the case of aluminium than that of sodium, to weaken the strong attractive forces between the metal ions and the delocalised electrons. These attractive forces in the case of aluminium can only be overcome at a comparatively higher temperature than that required for sodium. Therefore, the melting point of aluminium is higher than sodium.

Delocalised electrons: electrons that are not associated with any particular atom.

In a metal, the atoms are packed closely together in a regular arrangement called a lattice. Metal atoms in a lattice tend to lose their outer shell electrons and become positive ions. The outer shell electrons occupy new energy levels and are free to move throughout the metal lattice. We call these electrons delocalised electrons (mobile electrons). Delocalised electrons are electrons that are not associated with any one particular atom or bond.

Metallic bonding: the electrostatic attraction between positive ions and delocalised electrons. Metallic Bonding is strong. This is because the ions are held together by the strong electrostatic attraction between their positive charges and the negative charges of the delocalised electrons.

Lawrie Ryan and Roger Norris Solutions for Chapter: Chemical Bonding, Exercise 10: Questions

Lawrie Ryan Chemistry Solutions for Exercise - Lawrie Ryan and Roger Norris Solutions for Chapter: Chemical Bonding, Exercise 10: Questions

Questions from Lawrie Ryan and Roger Norris Solutions for Chapter: Chemical Bonding, Exercise 10: Questions with Hints & Solutions

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