Question

Explain the terms 'valency' and 'variable valency'.
How are the elements with variable valency named ?
Explain with an example,​

Answer 1

Answer:

The no. of hydrogen atoms which can be combined or displased by one atom of an element is called valency

Variable valency

Elements which show more than one valency are said to have variable valency

In variable valencies, the elctrons present in the outermost shell are used in bond formation but in certain circumstances one or more elctrons are used from inner shells and thus represent variable valency

Example

iron combines with chlorine atoms and sometimes with three chlorine atom...therefore it is said to exibit variable valency of +2 , +3

copper has two valencies......+1,+2