An element

A has atomic number 7, mass number 14

B has electronic configuration 2, 8, 8

C has 13 electrons, 14 neutrons

D has 18 protons 22 neutrons

E has electronic configuration 2, 8, 8, 1

State

(i) valency of each element

(ii) which one is a metal

(iii) which is a non-metal

(iv) which is an inert gas.

(i) Valency of each element:

Element A : Atomic number (number of electrons) = 7

Electronic configuration = 2, 5

Valency of A = 8 - 5 = 3

Element B : Electronic configuration 2, 8, 8

Valency of B = Zero

Element C : has 13 electrons

Electronic configuration = 2, 8, 3

Valency of C = 3

Element D : Protons = Electrons = 18

Electronic configuration = 2, 8, 8

Valency of D = Zero

Element E : Electronic configuration = 2, 8, 8, 1

Valency of E = 1

(ii) C and E are metals.

(iii) A is a non-metal.

(iv) B and D are inert gases.