Learning outcomes - after studying this topic, you should be able to:

• recognise that interactions of σ-orbitals gives rise to a valence bands, and σ* orbitals give rise to a conduction band in covalent networks
• use, define and explain the concepts of conduction band, valence band, band gap, hole, acceptor level, donor level, n-doping and p-doping
• explain the relationship between band gap and electrical and optical properties
• explain how n or p doping gives rise to conductivity of electrons and hole
• explain why the conductivity of semiconductors increases with temperature
• recognise a diagram of the band structure of insulators, metals and types of semiconductor.
   
• recall that the number of molecular orbitals increases with the number of atoms in a molecule

• Sections 7.2 and 7.8 (in Blackman, Bottle, Schmid, Mocerino and Wille, Chemistry, 3^rd Edition, 2015 (John Wiley) )