Q16 of 181 Page 302

How do electronic configurations of elements change in second period of periodic table with increase in atomic numbers ?

Electronic configuration of elements are as follows:

Lithium (2,1), Beryllium(2,2), Boron(2,3), Carbon(2,4), Nitrogen(2,5), Oxygen(2,6), Fluorine(2,7) and Neon(2,8).

How does the valency of elements vary in going down a group of the periodic table ?

Name the element which is in :

(a) first group and third period

(b) seventeenth group and second period.

Arrange the following elements in increasing order of their atomic radii.

Li, Be, F, N

Arrange the following elements in the in increasing order of their metallic character :

Mg, Ca, K, Ga