Question

Write the chemical formula of the followi.G compounds :(i) aluminium nitride (ii) ammonium phosphate. Name the element which shows avariable valency write the formula of its two chlorides.

Answer 1

(1). AlN

(2). (NH4)2SO4

(3). It is iron. Examples: FeCl2, FeCl3.

Answer 2

The Chemical  formula is written by crossing the valencies of the element involved in the compound.

Aluminium Nitride - AlN, since both Aluminium and Nitride have a valency 3

so we write Al3N3, but in science we do not write the valency if it is same for the elements involved. Therefore we will write - AlN

Ammonium Phosphate - (NH4)3 PO4 Here the numbers are subscript i.e. at the below of the element Symbol. In his the valency of NH4 ( Ammonium) is 1 and that of phosphate (PO4) is 3. after crossing the valencies we get the (NH4)3PO4

The most common element showing the variable valency is Carbon (C). It shows the valency of 2, 4, 6 which enables it to form abundant compounds on earth.