atomic mass

American  

[uh-tom-ik mas] / əˈtɒm ɪk ˈmæs /

noun

Chemistry.

1. the mass of an isotope of an element measured in units formerly based on the mass of one hydrogen atom taken as a unit or on 1/16 (0.0625) the mass of one oxygen atom, but after 1961 based on 1/12 (0.0833) the mass of the carbon-12 atom.

---

atomic mass British  

noun

1. the mass of an isotope of an element in atomic mass units

2. short for relative atomic mass See atomic weight

---

atomic mass Scientific  

1. The mass of a given atom or molecule, expressed in atomic mass units.

2. Compare atomic weight See also mass number

---

Etymology

Origin of atomic mass

First recorded in 1895–1900

Compare meaning

How does atomic-mass compare to similar and commonly confused words? Explore the most common comparisons:

• atomic weight vs. atomic mass
• atomic mass vs. atomic number
• mass number vs. atomic mass

Example Sentences

Since each of these 17 elements has a unique atomic mass — for example, only lead has an atomic mass of 0.34 trillion billionths of a gram — BSK could then determine the concentration of the metals.

From Los Angeles Times

"Many thousands of atomic nuclei that have yet to be measured may exist in nature," said Matthew Mumpower, a theoretical physicist and co-author on several recent papers detailing atomic masses research.

From Science Daily

An international team of researchers has found that ancient stars were capable of producing elements with atomic masses greater than 260, heavier than any element on the periodic table found naturally on Earth.

From Science Daily

Wallner is particularly interested in the radioactive iron isotope with the atomic mass of 60.

From Science Daily

Twelve, named for the atomic mass of carbon, has developed a process to make jet fuel using renewable electricity, water and waste biomass CO2 instead of fossil fuels.

From Seattle Times