Question

a)What is the fundamental difference in the electronic configuration between the Group 1 and

group 2 elements ?

b)On the basis of electronic configuration, how will you identify;

i) chemically similar elements ?

ii)the first element of a period?
​

Answer 1

Explanation:

a) The fundamental difference between the electronic configuration of group 1 and group 2 elements is that group 1 elements have 1 valence electron in their atoms whereas group 2 elements have 2 valence electrons in their atoms.

Since number of valence electrons varies from 1 to 8, therefore, the first element present in period 1 will have 1 valence electron and element present in last period will have 8 valence electrons (except in the first period where last element helium has only 2 valence electrons

Two different elements have similar chemical properties when they have the same number of valence electrons in their outermost energy level. Elements in the same column of the Periodic Table have similar chemical properties.

There are only two elements in the first period: hydrogen and helium. We can explain why there is less elements in the first row in modern theories of atomic structure. This is because in quantum physics, this period fills up the 1s orbital.