Question

The three elements boron, silicon and germanium belong to:
A.metals
B.non-metals
C.metalloids
D.all of the above

Answer 1

Metals mostly consist of s, d and f block elements. They form cations by losing electrons from their valence shells. Non-metals consist of p block elements. They are considered electron rich and form anions by adding electrons to their outermost shell to reach a stable configuration. The elements which show both the properties are called metalloids.

Complete step by step answer:
We shall first note down some of the main characteristics of the elements given in the question.
Boron is a group 13 element. Its atomic number is 5 and its electronic configuration is ${\rm{1}}{{\rm{s}}^{\rm{2}}}{\rm{2}}{{\rm{s}}^{\rm{2}}}{\rm{2}}{{\rm{p}}^{\rm{1}}}$. It has a bright lustre like metals but has low elasticity and is very brittle like non-metals. It is doped with silicon to produce p-type semiconductor. Thus, boron can be classified as a metalloid.
Silicon is a group 14 element. It has an atomic number of 14 with an electronic configuration of ${\rm{[Ne]3}}{{\rm{s}}^2}{\rm{3}}{{\rm{p}}^2}$. It can either lose four electrons to form a cation or gain four electrons to form an anion. Silicon also acts as a semiconductor. Thus, silicon is also a metalloid.
Germanium is also a group 14 element. It has an atomic number of 32 and is somewhat similar to silicon in its properties. Its electronic configuration is ${\rm{[Ar]3}}{{\rm{d}}^{10}}{\rm{4}}{{\rm{s}}^2}{\rm{4}}{{\rm{p}}^2}$. It can also act as a semiconductor. Like silicon, it can form both a cation and an anion. Thus, germanium is also a metalloid.
From the above, we can conclude that all the given elements are metalloids.

Hence, the correct answer is option C i.e., metalloids.

Note:
Some common differences of metals, nonmetals and metalloids are that while metals are conductors, non-metals are mostly insulators except for graphite and metalloids are mostly semiconductors. Metalloids have lustre but are non-malleable and non-ductile. They are also brittle with low elasticity. They mostly form covalent bonds.