Carbon and silicon both have four valence electrons each. How then are they distinguished?

The four valence electrons in carbon are in the second orbit but in silicon these are in third orbit. Hence, energy required to take out an electron from carbon is Eg = 5.4 eV but for silicon Eg = 1.1 eV. As a result carbon is an insulator but silicon is a semiconductor.
Class 12 Physics Chapter 14 Semiconductor Electronics Session 2024-2025.