Metallic sodium has high electrical conductivity.
(i) Metallic sodium is an example of conductor where the conduction band is partially filled and there is no band gap. Electronic configuration of Na is [Ar]3s¹.
(ii) Interaction of the partially filled 3s AOS of all the Na atoms gives rise to same number of Mos (molecular orbitals). All these closely spaced MOS together form a continuous band of energies which is called 3s band.
(iii) Lower half of 3s band corresponds of BMOS (bonding molecular orbitals) and is filled while the upper half of 3s band corresponds to AMOS (anti bonding molecular orbitals) and is empty.
(iv) There is no gap between these two halves.
(v) The 3s band in sodium is the conduction band which contains same number of electrons as the sodium atoms. This is responsible for the high conductivity of metallic sodium.
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