Question

how do you find the atomic mass/mass number of an atom

Answer 1

You can find the mass number and the atomic number in the periodic table.

E.g. >>> Look at the periodic table, and find the oxygen (O):
the mass number: 15,9994u
the atomic number: 8

And find the magnesium (Mg):
the mass number: 24,3050u
the atomic number: 12

Etc.
:)

Answer 2

Answer:

You can find the mass number and the atomic number in the periodic table.

E.g. >>> Look at the periodic table, and find the oxygen (O):

the mass number: 15,9994u

the atomic number: 8

And find the magnesium (Mg):

the mass number: 24,3050u

the atomic number: 12

Explanation: