Question

An atomic of an element has there electrons in its M shall :
a)write its electronic configuration and atomic no.
b)what is its valency
c)identify the element and also write it's natural

Answer 1

let element be X
1) K L M[since three electrons in M shell]
 2  8  3
and atomic no =2+8+3=13
2)valency=+3
c) X is Aluminium and it is metal 

Answer 2

a) electronic configuration
K L M
2 8 3=13
b) valency =+1
c)the element is lithium.