Distinguish between atomic number and mass number with an example.

Explanation

Atomic number and mass number : The number of protons present inside the nucleus is called atomic number . It is equal to the number of electrons in a neutral atom . The elements are characterized by their atomic numbers . Atomic number is denoted by Z.
Example : In sodium , Z = 11 , means that an atom of sodium contains 11 protons in the nucleus and 11 electrons outside the nucleus.
Mass number : Mass number indicates the sum of protons and neutrons present inside the nucleus. it is denoted by A.
Example : In sodium , Z = 11 , A = 23 , indicates that an atom of sodium contains 11 proton and (23 -11 ) = 12 neutrons.