Question

The bonding of silicon in molecules and solids is qualitatively the same as that of carbon. Silicon atomic states become molecular states analogous to those in Figure 10.14. and in a solid, these effectively form the valence and conduction bands. Which of silicon's atomic states are the relevant ones, and which molecular state corresponds to which band?

Short answer

Lower and higher states of $4\mathrm{N}$ form a band that qualifies as a Valence and Conduction band.

Step-by-step solution

Step-1:

For non-metals, the valence band is the highest range of electron energies in which electrons are normally present at absolute zero temperature, while the conduction band is the lowest range of empty electron states.

About the Valence band and Conduction Band:

The relevant atomic states are the four tetrahedral states at $\mathrm{n}=3$, that is the four $3{\mathrm{sp}}^3$ states. The four spatial states and two spins would form a band of $8\mathrm{N}$ states but this band actually splits into two because in the silicon-silicon band, the bonding and anti-bonding split. Then the lower of the$4\mathrm{N}$ states form a band that qualifies as the valence band and the higher of the states$4\mathrm{N}$ form a band that qualifies as the conduction bond..