Question

Intuitively it is relatively straight forward to see why sodium metal is a conductor, since for sodium the 3s band is half full as a consequence of the electron configuration, 1s2 2s2 2p 6 3s1 . In contrast magnesium, with one extra electron, has a closed shell configuration,

1s2 2s2 2p 6 3s2 , yet magnesium metal is also found to be a conductor.

Briefly explain why both sodium and magnesium metals are conductors.

Answer 1

Magnesium has the outer electronic structure 3s2. Both of these electrons become delocalised, so the "electron sea" has twice the electron density than that in sodium. The remaining "ions" also have twice the charge and so there will be more attraction between "ions" and "electron sea". Going from sodium to magnesium; the number of delocalised electrons increases. There are more electrons that can move and carry charge through the structure in the case of magnesium. Hence the electrical conductivity increases.

In the case of Mg, both BMO & ABMO are completely filled and hences the 3s es can easily jump to the higher energy 3p orbital.