1. Education
Send to a Friend via Email
You can opt-out at any time. Please refer to our privacy policy for contact information.

Discuss in my forum

Molecular Mass Definition

By

Molecular mass is the sum of the atomic masses in a molecule.

Molecular mass is the sum of the atomic masses in a molecule.

Lawrence Lawry, Getty Images

Molecular Mass Definition: A number equal to the sum of the atomic masses of the atoms in a molecule. The molecular mass gives the mass of a molecule relative to that of the 12C atom, which is taken to have a mass of 12.

Examples: The molecular mass of C2H6 is approximately 30 or [(2 x 12) + (6 x 1)]. Therefore the molecule is about 2.5 times as heavy as the 12C atom or about the same mass as the NO atom with a molecular mass of 30 or (14+16).

Return to the Chemistry Glossary Index

©2014 About.com. All rights reserved.