Sn, C, and Si, Ge are all group XIV elements. Yet, Sn is a conductor, C is an insulator while Si and Ge are semiconductors. Why?
Sn is a conductor because the energy gap for Sn is 0 eV, C is an insulator because the energy gap is 5.4 eV while Si and Ge are semiconductors because the energy
gaps are 1.1 eV and 0.7 eV respectively. These energy gaps are related to their atomic size and that makes one conductor, the other insulator and the rest