atomic mass
2 synonyms for atomic mass, grouped by meaning and by how common each one is.
Noun — The mass of a single atom, counted mainly from its protons and neutrons and usually given in atomic mass units, where one unit is a twelfth of the mass of a carbon-12 atom.
Synonyms
Rare, literary or technical
Precise, but they will stand out — check the sense before using one.
atomic weight
relative atomic mass
How to use atomic mass
The word patterns that sound natural to a native speaker.
atomic mass unit
average atomic mass
relative atomic mass
atomic mass number
Chemistry and physics. The value printed under each element on the periodic table is strictly the relative atomic mass, an average across the isotopes found in nature, which is why it is rarely a whole number.
Frequently asked questions
What is the difference between atomic mass and atomic number?
The atomic number is a count of protons and decides which element the atom is. The atomic mass is a measure of how heavy the atom is, and it depends on protons and neutrons together, so two atoms of the same element can share an atomic number but differ in atomic mass.
What is the difference between atomic mass and mass number?
The mass number is a whole number, the simple count of protons plus neutrons in one particular atom. Atomic mass is a measured quantity that comes very close to that count but is not exact, because binding energy and the tiny mass of electrons shift it slightly.
