Question

How does the number of valence electrons in atoms of metalloids explain why metalloids are semiconductors?

They have one or two valence electrons, so they cannot lose electrons easily.
They have one or two valence electrons, so they can lose or gain electrons.
They have three to six valence electrons, so they cannot lose electrons easily.
They have three to six valence electrons, so they can lose or gain electron

Answer 1

Correct choice: "They have three to six valence electrons, so they can lose or gain electron(s)."

Why: metalloids have an intermediate number of valence electrons and intermediate electronegativities between metals and nonmetals. That makes their bonding partly covalent and gives them a small band gap between the valence and conduction bands. As a result they do not conduct as freely as metals but can be made to conduct by adding or removing electrons (thermal excitation or doping). Example: Si (4 valence electrons) forms a covalent lattice (intrinsic semiconductor); doping with a 5‑valence atom (P) donates electrons (n‑type) while a 3‑valence atom (B) creates holes (p‑type). This ability to either lose or gain electrons is what makes metalloids good semiconductors.