ABSTRACT
Our simple description of metallic bonding and cohesion (Chapters III and IV) has given us a first insight into a good number of properties of this class of materials. However, it has a number of shortcomings. To note but one, it does not enable us to understand why silicon, a material with valency four which should be a very good conductor (high value of N in formula (48), p. 56) is a factor of ≃ 108 less conductive than silver (valency one) at room temperature.
