Question

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) and Ar(18)

Answer 1

Dear Student,

An atom has electronic configuration of 2, 8, 7

Atomic Number (Total number of electron) = 2 + 8+ 7 = 17

There are 7 valence electrons in the valence shell of the given element.

Electronic configuration

a) N = 2, 5
b) F = 2, 7
c) P = 2, 8, 5
d) Ar = 2, 8, 8

So, F(9) element have same number of valence electron.


Regards