Question

Write the formula and name of compound formed by following ion;
(a) sodium ion and sulphid ion .
(b) aluminum ion and phosphate ion.

Answer 1

HELLO THERE!

For forming compounds between a cation and an anion, what you must know is the charge of the ion, i.e, the valency of the element. Once that is known, we can use criss-cross method and exchange the valencies to get the formula of the compound formed.

Let's do it:

(a) Sodium ion and sulphide ion

Sodium ion: Na⁺

Sulphide ion: S²⁻

Hence, formula of the compound formed: Na₂S

Name of the compound: Sodium sulphide

(b) Aluminium ion and phosphate ion

Aluminium ion: Al³⁺

Phosphate ion: PO₄³⁻

Hence, formula of the compound formed: AlPO₄

Name of the compound: Aluminium Phosphate.

THANKS!