Mass number

Definition

The mass number is the total count of protons and neutrons in an atom's nucleus. It determines the atomic mass of an element, which is critical for understanding its properties and behavior at the chemical level.

Related terms

Proton:

A positively charged particle found in the nucleus of an atom that contributes to its mass number.

Neutron:

A neutral (uncharged) particle in an atom's nucleus that also contributes to the overall mass number.

Atomic Number:

The number of protons in an atom's nucleus, which uniquely identifies each chemical element on the periodic table