Question

Given below are the electronic configurations of some elements:

(a) 2,8,3

(b) 2,8,18,5

(c) 2,8,7

(d) 2,8,18,8,1

(e) 2,8,2

(f) 2,5

(g) 2,8,18,8

Answer the following:

(g) which is the first element of a period?

Answer 1

The first element of the period is:

1. The periods extend horizontally from left to right.
2. The groups extend vertically from top to bottom.
3. The element which has the minimum number of shells is the element which is the first element of the period.
4. The element having electronic configuration 2,5 is the first element of the period.