Theories band, of conductivity

Metals conduct electricity through conduction bands. Conduction bands arise from the application of Molecular Orbital theory to multi-atom systems. (See Chapter 10.) The bonding molecular orbitals and, sometimes, other molecular 

To gain a better understanding of the conductivity properties of metals, we must also apply our knowledge of quanmm mechanics. The model we will use to study metallic bonding is band theory, so called because it states that delocalized electrons move freely through bands formed by overlapping molecular orbitals. We will also apply band theory to certain elements that are semiconductors. 

The electrons in the Is, 2s, and 2p orbitals are localized on each Mg atom. Howevar, the 3s and 3p orbitals overlap to form delocalized molecular orbitals. Electrons in these orbitals can travel throughout the metal, and this accounts for the electrical conductivity of the metal. 

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The conductivity of metals generally decreases with increasing temperature. Give an explanation of this in terms of the band theory of conductivity. 

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