molecular weight

weight

 [wāt]

1. heaviness; the degree to which a body is drawn toward the earth by gravity. (See also Tables of Weights and Measures in the Appendix.) Abbreviated wt.

2. in statistics, the process of assigning greater importance to some observations than to others, or a mathematical factor used to apply such a process.

apothecaries' weight see apothecaries' system.

atomic weight the sum of the masses of the constituents of an atom, expressed in atomic mass units (or daltons), in SI units (i.e., kilograms), or as a dimensionless ratio derived by comparing the mass to the mass of an atom of carbon-12, which is taken as 12.000. Abbreviated At wt.

avoirdupois weight see avoirdupois system.

equivalent weight the amount of substance that combines with or displaces 8.0 g of oxygen (or 1.008 g of hydrogen), usually expressed in grams; for acid/base reactions, one equivalent donates or receives a mole of protons and the equivalent weight is the ratio of the molecular weight to the number of protons involved in the reaction. For oxidation-reduction reactions, one equivalent donates or receives a mole of electrons and the equivalent weight is the ratio of the molecular weight to the number of electrons involved in the reaction.

gram molecular weight the molecular weight of a substance expressed in grams; one gram molecular weight of a molecular substance contains one mole of molecules. See also mole¹.

low birth weight (LBW) see under infant.

molecular weight the weight of a molecule of a chemical compound as compared with the weight of an atom of carbon-12; it is equal to the sum of the weights of its constituent atoms and is dimensionless. Abbreviated Mol wt or MW. Although widely used, the term is not technically correct; relative molecular mass is preferable.

very low birth weight (VLBW) see under infant.

Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

mo·lec·u·lar weight (mol wt, MW),

the sum of the atomic weights of all the atoms constituting a molecule; the mass of a molecule relative to the mass of a standard atom, now ¹²C (taken as 12.000). Relative molecular mass (M_r) is the mass relative to the dalton and has no units.
See also: atomic weight.

Synonym(s): molecular mass, molecular weight ratio, relative molecular mass

Farlex Partner Medical Dictionary © Farlex 2012

mo·lec·u·lar weight

(mŏ-lekyū-lăr wāt)

The sum of the atomic weights of all the atoms constituting a molecule; the mass of a molecule relative to the mass of a standard atom, now ¹²C (taken as 12.000). Relative molecular mass (M_r) is the mass relative to the dalton and has no units.
See also: atomic weight
Synonym(s): molecular weight ratio, relative molecular mass.

Medical Dictionary for the Health Professions and Nursing © Farlex 2012

molecular weight

The sum of the weights of all the atoms in the molecule.

Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005

mo·lec·u·lar weight

(mol wt, MW) (mŏ-lekyū-lăr wāt)

The sum of the atomic weights of all the atoms constituting a molecule.
Synonym(s): molecular weight ratio, relative molecular mass.

Medical Dictionary for the Dental Professions © Farlex 2012