How do you determine the number of neutron?

Answer 1

Protons = Atomic Number

Electrons = Atomic Number

Neutrons = Atomic Mass - Atomic Number

*A note on Atomic Mass*

Atomic Mass is the sum of the number of protons and neutrons in an atom. Every time you remove or add a Proton/Electron or a Neutron, you change the mass by one.

*A note on Protons and Electrons*

The number of Protons and Electrons in an atom is always the same. Whenever you talk about adding/removing a proton or an electron, you are by default adding/removing one of the other as well.

Answer 2

The number of neutrons in an atom can be determined by subtracting the atomic number (number of protons) from the atomic mass (protons + neutrons). The atomic mass is usually listed on the Periodic Table for each element.

Answer 3

Number of neutron = Mass number - Atomic number