How can we figure out the number of electons

Subtraction of the number of protons from the mass number.

Explanation:

The number of protons in the nucleus of the atom is equal to the atomic number (Z). The number of electrons in a neutral atom is similar to the number of protons. The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus.

To determine the number of neutrons in an atom, we only have to subtract the number of protons from the mass number. Take note that the nucleus of an atom is composed of protons and neutrons. And the number of particles present in the nucleus is referred to as mass number (Also called atomic mass).

The number of protons in the nucleus of the atom is equal to the atomic number (Z). The number of electrons in a neutral atom is equal to the number of protons. The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus.