Question

What is Variable Valency? Do elements exhibit variable valencies? Give examples. [3 MARKS]

Answer 1

Definition: 1 Mark
Reason out: 1 Mark
Names of elements: 1 Mark

The valency is the number of the electrons that an atom gains , loses or even shares during a chemical reaction; that is the valency is the number of electrons that an atom needs to gain or lose in order to achieve noble gas electronic configuration.
Yes, sometimes the same element exhibits one valency in one compound and another valency in another compound. This property is called variable valency.

• Some elements show variable valency because of the different electronic configurations.
• An atom of an element can sometimes lose more electrons than that are present in its valence shell i.e. loss from the penultimate shell and hence exhibit more than 1 or variable valency.

Examples of elements with variable valencies: Copper, Iron, Lead etc.