Question

An element X which has mass no. 27 and atomic no. 13 exist in nature as metal.
a. Write the no. Of protons and neutrons present in it?
b. What is its valency?
c. Write a chemical formula of compound form when X react with chlorine?

Answer 1

First of all the element X is aluminium. .
The no. of proton of aluminium is equal to the atomic number which is 13
the no. of neutron of Al is =atomic mass - proton
=27-13
=14
it's valency is 3.

let Al reacts with Cl then .. The chemical compound formed will be

Al3+Cl = AlCl3

Answer 2

First of all the element X is aluminium. .

The no. of proton of aluminium is equal to the atomic number which is 13

the no. of neutron of Al is =atomic mass - proton

=27-13

=14

it's valency is 3.

let Al reacts with Cl then .. The chemical compound formed will be  

Al3+Cl = AlCl3