To find the number of neutrons in an atom, what we must do is to follow the following steps:
1) Find the element in the periodic table.
2) Find the atomic number of the element. The atomic number is the number of protons of a single atom of that element.
3) Find the atomic weight of the element.
4) Finally, we look for the number of neutrons. For this, we follow the following relationship:
Atomic weight - number of protons = number of neutrons.
Answer:
To find the number of neutrons in an atom, you would subtract:
B.) atomic number from mass number