Describe the relationship between the atomic number, mass number, number of protons, number of neutrons.

Atomic number (Z) = Number of the protons

It means that if the atomic number of C is 6, it implies that the number of protons in carbon is 6 too.

Mass number (M) = Number of the protons + Number of the neutrons

It means that if the atomic mass of C is 12, it implies that the number of protons and the neutrons in carbon is 12.