Question

What is the difference between the mass number and the atomic number of an atom?

Answer 1

The atomic number of an atom is the number of protons inside in this atom.
Atomic number of an atom=Z

The mass number of an atom is the number of protons + number of neutrons in this atom.
mass number of an atom=A

A=Z+N

A=mass number.
Z=atomic number
N=number of neutrons.

Answer 2

Atomic number is the number of protons that are inside that atom. This helps identify which element an atom is.

Atomic mass is the number of protons and neutrons inside an atom.