Question

Write chemical formulae of the following
compounds ?
(a) aluminium nitride (b) ammonium phosphate
​

Answer 1

Answer:-

(a) Aluminum Nitride-

$\star$ To write chemical formulae, we need to know the valency of the elements in the compound.

Valency:-

It is the number of electrons present in the outermost shell of an electron. It determines whether the atom will lose/gain electrons.

The valency of Aluminum is 3+(positive charge),

It is written as ${Al}^{3+}$

The valency of Nitride is 3-(negative charge)

It is written as ${N}^{3-}$

To write a formula,

The valency of an element is cross multiplied with the other. The no. of atoms of the element is determined by doing this.

Element $<strong>A</strong><strong>l</strong><strong> </strong>$ , $<strong> </strong><strong> </strong><strong>N</strong><strong> </strong>$

Valency. 3, 3

If the valencies are reduced to their lowest forms before cross multipltying.

Here,

3 and 3 can be reduced to 1 and 1

So,

Aluminum Nitride can be written as

$\fbox {{Al}{N}}$

(b) Ammonium Phosphate:-

Valency of Ammonium is 1+

It is written as ${{NH}_{4}}^{1+}$

Valency of Phosphate is 3-

It is written as ${{PO}_{4}}^{3-}$

Element ${NH}_4$ , ${PO}_4$

Valency 1 , 3

Therefore,

Ammonium Phosphate can be writte as

$\fbox {({NH}_4)_{3}{PO}_4}$