Question

Why is Silicon a semiconductor?

Answer 1

Silicon is a metalloid present in the ${14^{{\text{th}}}}$ group of the periodic table. It presents below carbon in the modern periodic table. It has $4$ valence electrons in outermost orbit and it can form covalent bonds with other elements.

Complete answer:
Silicon is a ${14^{{\text{th}}}}$ group element which shows metalloid behavior and has $4$ valence electrons in the outermost orbital for the formation of covalent bonds. Silicon always forms covalent bonds with other compounds due to these $4$ valence electrons.
Due to its properties of metalloid, it acts as a semiconductor.
Semiconductors are those materials which have an intermediate energy difference between the covalence band and the valence band between metals and nonmetals. Covalence bant and valence bands of metals are overlapped whereas non-metals have large gaps between them. Due to which metals conduct electricity but non-metals not and the semiconductors are intermediate between them.
When a large number of silicon atoms combine to form a single crystal it shows the property of semiconductors.
Semiconductors have many uses in industries and many other places like manufacturing of pn junction diodes, many more diodes, transistors etc.
Semiconductors are of two types intrinsic and extrinsic type semiconductors, this depends on the type of doping performed on the pure element like silicon.

Note:
Semiconductors (silicon) are doped to generate either a surplus or a deficiency in valence electrons. Doping allows researchers to exploit the properties of sets of elements, referred to as dopants, in order to modulate the conductivity of a semiconductor.