If Z = 3, what would be the valency of the element? Also, name the element.

Answer :  

Given Z= 3

we know that Z = Atomic Number = Number of protons = Number of electrons

:.  Number of electrons = 3

Distrubution of electrons is given by the formula 2n² where n is the number of orbit or shell represented by letters K, L, M, N etc

Hence for first orbit i.e. 'k' the number of electrons = 2 × 1 = 2

for second orbit i.e. 'L' the number of electron = total electrons - numbers of electrons in 'K' = 3-2=1

Valency of element is 1 as it will readily lose its outermost valance electrons than to gather 7 more to have a fully filled outermost orbit.

The element is Lithium 

This is an answered question from Chapter 4. Structure Of The Atom of CBSE Class 9th Science

Check for Complete Exercise Solution for Chapter 4. Structure Of The Atom | CBSE Class 9th Science