Skip to main content
Glite Dictionary
atomic mass

atomic mass

1 3.6
A number that tells how heavy one atom of an element is in atomic mass units
  • noun
  • /əˈtɑːmɪk mæs/
  • Specialized
translation icon : masa atómica
  • When calculating the atomic mass, scientists consider both protons and neutrons in the atom.
  • relative atomic mass

So you need that huge electron electromagnet to separate out the different atomic masses.

Examples

  • The work with carbon actually began in 1984 at Exxon, where Andrew Kaldor had put graphite in his apparatus and seen intriguing mass peaks at a host of even multiples of the atomic mass of carbon.

    Academic text (1996)

  • OK, so you're sayin' I add up the atomic masses of the proton and the neutron, right?

    Me, Myself & Irene (2000)

  • The atomic number remains the same after a capture event, but the atomic mass increases.

    Academic text (2005)

  • Thus, low-mass stars are responsible for most of the elements with atomic masses around 90 or so.

    Academic text (2005)

  • The isotopes will also have a slightly different atomic mass because of the different number of neutrons.

    Blog text (6)

  • That number, Avogadro's constant, links these atomic masses to grams.

  • Soddy realized that there could be versions of an element whose atomic masses differed, even though their chemical properties were the same.

    Academic text (2012)

  • In 1920, Rutherford proposed that the difference between the atomic number of a nucleus and its atomic mass might be due to neutral particles in the nucleus.

    Academic text (2012)

  • Carbon dioxide (CO2) isotopologues can have masses of 44, 45, or 46 atomic mass units, depending on the nuclides that compose them.

    Academic text (2011)

  • The atomic mass of carbon-12 is defined as exactly 12 atomic mass units.

Synonyms

atomic weight
vsatomic mass
  • Specialized
2 3.9

The average mass of the atoms of a chemical element, measured in atomic mass units

is the mass of a single atom rather than an average
relative atomic mass
vsatomic mass
  • Specialized
5.3

The mass of an atom compared with one twelfth of a carbon-12 atom

is the raw mass value given without comparison to that standard

Surface Forms

atomic mass singular
atomic masses plural

Morphology

atomic + mass

The meaning 'mass of an atom' is directly and compositionally derived from 'atomic' (relating to atoms) + 'mass' (amount of matter), so a learner who knows both words can infer the MWE. This noun–noun compound follows regular compositional patterns and has clear equivalents across many languages, making it transparent despite being a technical term.

Etymology

Atomic mass simply means the mass of an atom. Early scientists wanted an easy number to 'compare' how heavy one atom is to another, so atomic mass became the name for that number used to tell an atom's weight.