Question

Question #700fe

Answer 1

Subtract the atomic number from the mass number to find the number of neutrons.

Explanation:

For example Boron has an atomic number of 5. It has a mass number of 10.8. This means that approximately 80% of Boron atoms have a mass of 11 and 20% of Boron atoms have a mass of 10.

The isotope Boron 11 `B_5^11` has 5 protons with a mass of 5 amu

`11 - 5 = 6` This means that the atom has 6 neutrons. While

The isotope Boron 10 `B_5^10` has 5 protons with a mass of 5 amu

`10 - 5 = 5` This means that the atom has 5 neutrons .

The mass number is the sum of the protons and neutrons. So to find the number of neutrons subtract the protons from the mass number.