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Glite Dictionary
relative molecular mass

relative molecular mass

5.6
The mass of all the atoms in one molecule compared with one twelfth of a carbon-12 atom
  • noun
  • Specialized
translation icon : masa molecular relativa
  • The relative molecular mass of water is approximately 18, which accounts for the two hydrogen atoms and one oxygen atom.

Examples

  • Studies with endoglycosidases suggest that this increase in apparent relative molecular mass is due to an increase in the average size of the N-glycan chain present on band 3.

    Academic text (1996)

  • Chemists often use the relative molecular mass to determine the amount of a substance needed for a reaction.

  • When calculating the relative molecular mass, it is important to sum the relative atomic masses of all atoms in the molecule.

Synonyms

molecular weight
vsrelative molecular mass
  • Specialized
2 3.5

The total mass of the atoms in a molecule

is defined by comparison to one twelfth of the carbon twelve isotope

Surface Forms

relative molecular mass singular
relative molecular masses plural

Morphology

relative + molecular + mass

The phrase composes straightforwardly from 'molecular' (concerning molecules) and 'mass' so a learner who knows the words will infer it refers to the mass of a molecule, and 'relative' signals a comparison to a standard. However, the precise technical definition (sum of relative atomic masses referenced to one‑twelfth of carbon‑12) is specialized and not fully derivable from the parts alone, so the term is only partially predictable.

Etymology

Relative molecular mass literally means the mass, meaning weight, of a molecule given as a number relative to a chosen 'standard' atom such as carbon-12. You get it by adding the weights of all the atoms in the molecule and comparing that total to the 'standard', so the number tells you how heavy the molecule is compared with that reference.