atomic mass

noun

: the mass of an atom usually expressed in atomic mass units

also : atomic weight

Examples of atomic mass in a Sentence

Recent Examples on the Web

The researchers suggest that nothing with an atomic mass above nine would be able to escape the atmosphere. — John Timmer, ArsTechnica, 16 July 2026

Different isotopes of an element all have the same number of protons, but a different number of neutrons, and thus, a different atomic mass. — Adam Harrington, CBS News, 9 Dec. 2025

Its atomic mass is slightly higher than regular hydrogen, thanks to that extra neutron. — Keith Cooper, Space.com, 17 Oct. 2025

How changes in atomic mass leave clues to our climatological past. — Dan Zak, Washington Post, 15 July 2019

Some have theorized that the soda got its name from the atomic mass of lithium, which is roughly seven. — Beth Mole, Ars Technica, 22 Sep. 2017

Not only should the chemistry of the two isotopes be the same, the slight difference in atomic mass largely washes out in the watery environment of the body. — Jennifer Ouellette, Quanta Magazine, 2 Nov. 2016

Word History

First Known Use

1848, in the meaning defined above

Rhymes for atomic mass

• bermudagrass
• ecclesiastes
• alas
• amass
• bromegrass
• bypass
• crabgrass
• crevasse
• eelgrass
• eyeglass
• groundmass
• harass

Kids Definition

atomic mass

noun

: the mass of any kind of atom usually expressed in atomic mass units

Medical Definition

atomic mass

noun

: the mass of an atom usually expressed in atomic mass units

also : atomic weight compare mass number