Question

Four elements P, Q, R and S belong to the third period of the Modern Periodic Table and have respectively 1,3, 5 and 7 electrons in their outermost shells. Write the electronic configurations of Q and R and determine their valencies. Write the molecular formula of the compound formed when P and S combine.

Answer 1

Electronic configuration of Q = 2, 8,3

Valency of Q =3

Electronic Configuration of R = 2,8, 5

Valencyof R=8-5=3 

Electronic configuration of P = 2,8,1

Electronic configuration of S=2,8,7 

Formula : PS/NaCl