# What does the mass number tell us?

Jul 3, 2014

Each element has a specific mass number and a specific atomic number.These two numbers are fixed for an element.

The mass number tells us the number (the sum of nucleons) of protons and neutrons in the nucleus of an atom.

The atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom.
It is traditionally represented by the symbol Z.

The atomic number uniquely identifies a chemical element. In an atom of neutral charge, atomic number is equal to the number of electrons.

The atomic number is closely related to the mass number, which is the number of protons and neutrons in the nucleus of an atom.

Mass  of Carbon is 12, and its atomic number is 6.

A Carbon atom has atomic  6 , so it has 6 protons in its nucleus.

it has mass number 12 , it means that the sum of neutrons and protons in a carbon atom is 12.

n + p =12

p =6

n +6 = 12

n+6-6 = 12-6

n=6.