question_answer

Given below are some elements of the modern periodic table. Atomic number of the element is given in the parentheses:

A(4), B(9), C(14), D(19), E(20)

(a) Select the element that has one electron in the outermost shell. Also write the electronic configuration of this element.

(b) Which two elements amongst belong to the same group? Give reason for your answer.

(c) Which two elements amongst these belong to the same period? Which one of the two has bigger atomic radius?

Answer:

A = 2, 2

B = 2, 7

C = 2, 8, 4

D = 2, 8, 8, 1

E = 2, 8, 8, 2

(a) D = 2, 8, 8, 1

(b) A and E, as they have same number of valence electrons.

(c) A and B, D and E as their number of shells are same, A is bigger than B and D is bigger than E.