Question

how do scientists determine the number of neutrons in an isotope of an atom

Answer 1

For example Carbon-13. Normal Carbon has only 6 electrons, 6 protons, and 6 Neutrons. The way to find the number of Neutrons in an isotope it to take the number after the element and subtract it by how many protons it has. So in this case you would take 13 and subtract 6 from it. Thus giving you 7 Neutrons.