Question

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

Copper [II] oxide

Answer 1

Write the formula of

Copper [II] oxide	Symbol	Valency
Copper	\[\ce{Cu}\]	\[\ce{2^{+}}\]
Oxide	\[\ce{O}\]	\[\ce{2^{-}}\]

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

The Formula is CuO