Question

What do you mean by variable valency? Give example.

Answer 1

Variable valency:
● There are some elements which show different valencies in different compounds.
For example, Copper shows two valencies 1 and 2. In the red oxide of copper, its valency is 1, while in the black oxide its valency is 2.
Similarly, iron shows valencies of 2 and 3, and gold shows valencies of 1 and 3.

● The compound in which element shows the higher valency is indicated by the suffix -ic, while the compound in which the elements show the lower valency is indicated by the suffix -rous.
● For example, the black oxide of copper is called cupric oxide, while the red oxide of copper is called cuprous oxide.