Define the terms atomic number and atomic mass number of an element.

1. Atomic number: The number of protons present in the nucleus of an atom is known as the atomic number. It is denoted by ‘Z’.

2. Atomic mass number: The total number of protons and neutrons present in the nucleus of an atom is known as mass number. It is denoted by A.Generally atomic number and mass number of the atom of an element is represented by a symbol $Z_A^X$

'X’ is an element.