Question

Electronic configuration of elements P, Q, R and S are given below. (Symbols not real)

P - 2, 2
Q - 2, 8, 2
R - 2, 8, 5
S - 2, 8

(i) Which among these elements are included in the same period? [ 1 Mark]

(ii) Which are those included in the same group? [1 Mark]

(iii) To which group and period does the element R belong? [1 Mark]

Answer 1

The position of element P, Q, R, and S are:
P - 2, 2
Here we have 2 shells and 2 valance electrons so element P belongs to period 2, group 2.

Q - 2, 8, 2 :
Here we have 3 shells and 2 valance electrons so element Q belongs to period 3, group 2.

R - 2, 8, 5
Here we have 3 shells and 5 valance electrons so element P belongs to period 3, group = (10+5) = 15

S - 2, 8 : Period 2, group 18
Here we have 2 shells and 8 valance electrons so element P belongs to period 3, group = (10+8) = 18

(i) P and S, Q and R - belongs to same period. [ 1 mark]

(ii) P and Q, belongs to same group. [ 1 mark]

(iii) element R belongs to 3rd period and 15th group. [ 1 mark]