Definition

1. Noun:
   • A unit of measurement in chemistry: The gram molecule is the molecular weight of a chemical substance expressed in grams. It is the basic unit of amount of substance in the International System of Units (SI), equivalent to one mole.

Usage

• The term "gram molecule" is used in scientific contexts, particularly chemistry and physics, to quantify an amount of substance. It specifies that the numerical value of a substance's molecular weight is taken in grams, representing one mole of that substance.

Examples

• Noun:
  • The gram molecule of water (H₂O) is approximately 18 grams, as its molecular weight is about 18 atomic mass units.
  • In the experiment, we needed one gram molecule of sodium chloride.
  • The concept of the gram molecule simplifies stoichiometric calculations.

Advanced Usage

• Historical Context: The term "gram molecule" is largely synonymous with the modern SI unit "mole" (symbol: mol). While "mole" is the preferred term in contemporary scientific literature, "gram molecule" may still be encountered in older texts or specific educational contexts to emphasize the mass aspect.
  • Early chemistry textbooks often referred to the amount of substance as a gram molecule.

Variants and Related Words

• Mole (n): The modern SI base unit for amount of substance, defined as containing exactly 6.02214076×10²³ elementary entities (atoms, molecules, ions, or other particles). One mole of a substance has a mass in grams equal to its molecular or atomic weight.
  • One mole of carbon-12 atoms has a mass of exactly 12 grams.

Synonyms

• Mole: The standard contemporary term for the same unit of amount of substance.

Noun

1. the molecular weight of a substance expressed in grams; the basic unit of amount of substance adopted under the Systeme International d'Unites