Question

1. An atom has electronic configuration of 2, 8, 7 (a)What is the atomic number of the element? (b)Which of the following elements have same number of valence electrons N(7), F(9), P(15), Ar(18)

Answer 1

a. Atomic number is equal to sum of ec

= 2 + 8 + 7

= 17.

b. Valence e- in N = 5
Valence e- in F = 7
Valence e- in P = 5
Valence e- in Ar = 0

Hence N and P have same no. Of Valence electrons.

Hope it's helpful to u.

Answer 2

a)
Atomic number is equal to the number of protons which is equal to number of electrons as electronic configuration is given 2, 8, 7 and if we add 2 + 8 + 7 which are electrons is equal to 10 + 7 equal to 17 so atomic number is equal to 17......

b)
N(7)=2,5 valency e-=5
F(9)=2,7 valency e-=7
P(15)=2,8,5 valency e-=5
Ar(18)=2,8,8 valency e-=8
Element N and element P is having same number of Valence Electrons......