How do scientists determine the number of neutrons and isotopes in an atom?

Answer 1

Atomic Mass minus atomic number.

This is rather simplified but the atomic mass of an element is the total of all the protons, neutrons, and electrons in an atom. Each proton and neutron has an atomic mass of approximately 1 AMU (atomic mass units) while an electron has an atomic mass of about 0.0005 AMU. So, you don't need to worry about the electrons.

The atomic number of an element is simply the number of protons in the atom.

So, atomic mass (number of protons and neutrons) minus atomic number (number of protons) equals number of neutrons in an atom.

Answer 2

You subtract the atomic number from the atomic mass to determine the number of neutrons in an isotope.

Answer 3

Scientists determine the number of neutrons and isotopes in an atom by first finding what the atomic mass and the atomic number of the element is.