Properties and uses of boron and silicon

Boron

Boron is unreactive to most chemical reagents at ordinary temperature. It reacts only with strong oxidizing agents such as fluorine and concentrated nitric acid at room temperature. However, it combines with metals at very high temperatures to form borides, which are generally hard and high melting solids. Some reactions of boron are:

With oxygen

action of boron with oxygen

With nitrogen

action of boron with nitrogen

With halogens

action of boron with halogens

With acids

action of boron with acids

action of boron with nitric acid

With alkalies

action of boron with alkali

With metals

action of boron with metals
(except Cu, Ag, Au)

action of boron with magnesium

With steam

action of boron with steam
s

Uses of boron

  • As a deoxidizer in the form of its salts such as calcium boride.
  • As a moderator in nuclear reactors.
  • As an abrasive and a refractory material.

Problem

1. Explain the following a) Boron is trivalent b) the action of boron on mineral acids.

Solution

(i) Boron's atomic number is 5. Its electronic configuration is 1s2 2s2 2p1. Hence it can lose 3 electrons from the second orbit to form bonds, as the new configuration is more stable.

(ii) Boron reacts with strong oxidizing acids like concentrated sulphuric or concentrated nitric acid to give boric acid.

But boron shows no action with hydrochloric acid as it is less reactive and needs strong oxidizing atmosphere.

Silicon

Silicon is a very important component of ceramics, glass and cement. Ge is transparent in the infrared region and therefore is used in the making of infrared windows, prisms and lenses.