# Mass Number

## Key Questions

• #### Answer:

Well, the mass number of an atom is simply the number of massive, nuclear particles, protons, and neutrons....

#### Explanation:

And so for ""^1H, the mass number is simply 1; for ""^2H, the mass number is simply 2; for ""^3H, the mass number is simply 3. The isotopes contain $\text{0, 1, 2 NEUTRONS}$ respectively.

Most of the heavier atoms have a range of isotopes, and the quoted atomic mass on the Table is the weighted average of the isotopic masses..

• #### Answer:

The total amount of protons and neutrons

#### Explanation:

It's important to remember that mass number is not the same as atomic mass. In physics the mass number is indicated with an A, and varies for every atom in the periodic table, and even for the same atom if it has isotopes.