Step-by-step explanation:
Atomic mass: The sum of no. of protons and no. of neutrons
Protons: a subatomic particle with a positive charge
Neutron: a subatomic particle with no charge (neutral)
Isotopes: the same elements with different atomic mass [Eg. uranium-235, uranium-238. Uranium being one element, can have different mass numbers. Hence Uranium-238 is an isotope of Uranium-235]
Therefore:
Proton + neutrons= Atomic mass
Δatomic mass= formation of isotopes.
*Δ= Change in