Question

How many neutrons are in an atom of chlorine?

Answer 1

Hint: The number of neutrons can be found by the atomic mass of the element. So, first, find the atomic number which will tell the number of electrons, and protons in the atom and then take the difference of atomic mass and number of protons or electrons, this will give the number of neutrons.

Complete answer:
As we know that in an atom there are mainly three components: electrons, protons, and neutrons. Those that have a negative charge and revolve around the nucleus are electrons, those who have a positive charge and remain in the nucleus are protons, and those who do not have a charge and remain in the nucleus are neutrons.
Chlorine is the element of group 17 of the p-block and its atomic number is 17. This means that there are 17 electrons in the chlorine atom. Since in an electrically neutral chlorine atom the number of protons will be the same as the number of electrons. So, the number of protons will also be 17.
Now to find the number of neutrons in the atom we should know the atomic mass of the chlorine atom and the atomic mass of the chlorine atom 35. We have to take the difference of atomic mass and number of protons or electrons, this will give the number of neutrons.
So, the number of neutrons will be:
$35-17=18$
Therefore, there are 18 neutrons in the chlorine atom.

Note:
It is not necessary that the number of neutrons is the same as the number of protons or electrons. In some atoms like nitrogen, oxygen, etc the number of electrons, protons, and neutrons are the same.