4CH1

Metallic Bonding

Principles of Chemistry · 2 question types

Practise

Metals as giant lattices

  • A metal is a giant metallic lattice of metal atoms packed in a regular arrangement
  • Each atom releases its outer-shell electrons into the lattice
    • These electrons are no longer attached to any single atom
    • They are described as
    • They move freely throughout the whole lattice, forming a
  • What remains at the lattice positions are the positive metal ions (cations)

What the metallic bond is

  • The metallic bond is the electrostatic attraction between the positive metal ions and the surrounding delocalised electrons
  • The attraction acts in every direction through the lattice and holds the whole structure together
  • The same bonding model applies to pure metals and to alloys, which are mixtures of a metal with one or more other elements
Metallic-bonding lattice — positive metal ions in a regular arrangement surrounded by a sea of delocalised electrons from the outer shells of the metal atoms, free to move throughout the structure
Source: Metallic bonding by Save My Exams
Exam tip

Describing the metallic bond

Asked to describe the attractions in metallic bonding (2 marks, set once in the 23 papers), give both halves of the electrostatic attraction, one mark each: the positive metal ions ("the nuclei of the metal atoms" is also accepted) and the delocalised electrons between them. Any mention of ionic bonding, sharing electrons or intermolecular forces loses both marks. The same idea, with "strong" in front, is the credited reason for a metal's high melting point. Asked to label a printed lattice diagram, use "positive ion" (or cation) and "delocalised electron": "atom" is allowed for the first, "proton" is rejected.