What is mass number of an element? How is the mass number related to the protons and neutrons present in the nucleus of an atom?

The total number of protons and neutrons present in the nucleus of an atom is called the mass number.

The number of protons and neutrons combined to give us the mass number of an atom.

It is represented using the letter ‘A.’

As both protons and neutrons are present in the nucleus of an atom, they are together called nucleons.

For example, an atom of carbon has 6 protons and 6 neutrons. Thus, its mass number is 12.

While the number of protons remains the same in all atoms of an element, the number of neutrons can vary. Thus, atoms of the same element can have different mass numbers, and these are called isotopes.

The atomic number of an element is determined by the number of protons in it, and it is used to differentiate one element from another. The mass number of an element is determined by the number of protons and neutrons combined.

The atomic number is equal to the number of protons.

Atomic mass is equal to the sum of the number proton and number neutron.