Question

Write the chemical formula of the following compound in a step-by-step manner –

Copper [I] sulphide

Answer 1

Write the formula of

Copper [I] sulphide	Symbol	Valency
Copper	\[\ce{Cu}\]	\[\ce{1^{+}}\]
Sulphide	\[\ce{S}\]	\[\ce{2^{-}}\]

Step I – Write each symbol with its valency.
Positive ion is written first
\[\ce{Cu}^{1+}\]  \[\ce{S}^{2-}\]
Step II – Interchange the valencies ignoring the signs.

The Formula is \[\ce{Cu2S}\]