Question

Atomic number and mass number of an element are 11 and 23 . Find the number of proton , neutron and valency

Answer 1

Atomic number = No of protons = 11
Now
Mass number = No of protons + No of neutrons
23 = 11 + No of neutrons
no of neutrons = 12.
Now for an atom to be electrically neutral the no of electrons will be equal to the no of protons.
Thus no of electrons = 11
Electronic configuration = 2,8,1
Thus it's valence electrons in its outermost shell= 1
Therefore it's valence = 1.

Answer 2

Atomic number = protons = electrons
So, proton = 11

Mass number= proton + neutron
Mass number - proton = neutron
23 -11 = 12
So, neutron = 12

Element = Sodium
Atomic number = 11
Electronic configuration = 2,8,1
Valency = +1