A single neutron has a mass of 1.008665 atomic mass units. An atomic mass unit is a very small unit of mass equal to one-twelfth of the mass of a carbon-12 atom. Neutrons have a slightly larger mass than protons, which have a mass of 1.007277 atomic mass units.
The mass of neutrons and protons can be used to calculate an atom's atomic mass, which is equal to the combined mass of the neutrons and protons in its nucleus. Atomic mass, which is expressed in atomic mass units, can be calculated by multiplying the number of neutrons by 1.008665 and the number of protons by 1.007277, and then adding these two products together.
Neutrons are atomic particles that carry a neutral charge and are found in the nuclei of atoms. Atoms of an element that contain different numbers of neutrons are called isotopes. An element's average atomic mass is calculated by multiplying the mass of each isotope by its relative abundance in nature, and then adding these products together. Generally, the atomic mass displayed for each element on the periodic table is the average mass of all of its natural isotopes. Sometimes atomic mass is rounded to the nearest whole number; this number is known as an element's mass number.