carbon 12

American  

Also carbon-12

noun

1. the isotopic carbon atom that comprises 99 percent of naturally occurring carbon, and that since 1961 has been used as the standard for atomic weight by representing a unit of 12.00000.

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carbon 12 Scientific  

1. A stable isotope of carbon, having six protons and six neutrons in the nucleus. Carbon 12 makes up most naturally occurring carbon.

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Etymology

Origin of carbon 12

First recorded in 1940–45

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Compare meaning

How does carbon-12 compare to similar and commonly confused words? Explore the most common comparisons:

• carbon 12 vs. carbon 14

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Example Sentences

See Examples For:

carbon 12

But if Perseverance’s sample is found to contain not only methane but methane rich in an isotope called carbon 12, that could change.

From Scientific American ● Nov. 10, 2021

The vast majority of the carbon in the atmosphere is carbon 12, a stable atom with six protons and six neutrons.

From Seattle Times ● Oct. 21, 2021

There’s carbon 12 and its ever-so-slightly-heavier sibling, carbon 13.

From Washington Times ● Jun. 11, 2017

The element carbon usually has six protons and six neutrons, and when it does it is called carbon 12.

From Forbes ● May 21, 2010

The machine separates carbon 14 and carbon 12, an atom that also accumulates at a steady rate but does not decay, from all other atoms in the sample.

From Time Magazine Archive

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