Relate the electronic configuration of elements and their properties in the classification of elements.

Explanation

The chemical properties of all elements depends upon the electronic configuration Upon the basis of complete and incomplete electron shells and chemical properties, the elements are classified into four types. (Type-I, Type-III and Type -IV).
Type- I(inert gas elements): All the elements with an electronic configuration `ns^(2) np^(6)` including He belongs to this type. nth shell of those elements are completely filled. The elements show chemical inertness due to completely filled shells and hence they have extra stability. Because of their stability, they are chemically inactive. Eg: He, Ne, Ar, Kr, Xe and Rn
Type-II (Representative elements): Except inert gases, the remaining elements of s and p-blocks are called representative elements. All the elements with an electronic configuration `ns^(1)` to `ns^(2) np^(5)` excluding. He comes under this type These are atoms in which all except the outermost shells `(n^(th))` are complete. Elements of this type enter into chemical combination by lossing, gaining or sharing electrons to get stable inert gas configuration. Many of the metals, all non-metals and metalloids come under this type. Chemically these elements are reactive.
Type-III (Transition elements): All the elements with an electronic configuration `(n-1) d^(1-9) ns^(1 or 2)` belongs to this type. Atoms in which the two outermost shells are incomplete. These elements show variable oxidation states, form complex ions and coloured ions. The electronic configuration of d-block elements is `(n-1) d^(1-10) ns^(1-2)`. Small size, high nuclear charge and unpaired .d. orbitals impart characteristic properties to be transition elements.
Type- IV (Inner transition elements): All the elements with an electronic configuration `(n-2) f^(1-14) (n-1) d^(0, 1) ns^(2)` belongs to this type. Atoms in which three outermost shells are incomplete. Lanthanides and Actinides belong to this type.