Question

Why s and p block elements are called representative elements.and what is representative mean?

Answer 1

Representative or normal elements -

Elements which have all the shell complete except outermost shell which is incomplete are called representative elements. The number of electrons in the outermost shell varies from 1 to 7 ie - the configuration of outermost shell varies from ${ns}^{1}to{ns}^{2}to{np}^5$ . These elements comprises of some metals , all non -metals and metalloids. These are the elements which are found in nature in abundance and active in nature. On account of this these elements are called representative elements. All the three types of valencies are observed in the case of these elements. These elements have one of the following configurations in their outermost shell -

${ns}^1,{ns}^2,{ns}^2{np}^1,{ns}^2{ns}^2,{ns}^2{np}^3,{ns}^2{np}^4,{ns}^2{np}^5$

$1,2,3,4,5,6,7$

The number of electrons present in the outermost shell signify the group to which these elements belongs.