Question

How many total electrons and valence electrons are found in an atom of each of the following elements? What is the number of the principal energy level in which the valence electrons are found?

A )Mg         D) B

B) K            E) Ar

C) C            F) Xe

Answer 1

A) Mg atomic number = 12 = 12 electrons are present.

Mg is 2nd group   so 2 valency electrons present

B) K = 19 electrons

               1 valency electrons

C) C = 6 electrons

               4 valency electrons

D)     B = 5 electrons

                    3 valency electrons

E)   Ar   = 18 electrons

                  8   valency electrons

F)         Xe    =   54 electrons

                             8 valency electrons