Question

Magnesium (Mg) has 12 protons and an atomic mass of 24. How many neutrons does magnesium have?

Answer 1

An atom is made up of three different particles, which are proton, neutron and electron. The proton and the neutron are located in the nucleus of the atom and they make up mass of the atom. The electron orbit around the nucleus. The proton is positively charged while the electron is negatively charged, thus, for the atom to remain neutral, the number of proton and electron in an atom must be equal. The neutron has no charge.
The atomic mass of an element = number of proton + number of neutron
Atomic mass of magnesium= 24 
Number of proton = 12
Therefore, number of neutron = 24 - 12 = 12.
Thus, the number of neutron = 12.

Answer 2

The number of neutrons can be found by subtracting 12 from 24 which will mean that there is 12 neutrons