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.

carbon 12

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

Word History and Origins

Origin of carbon 12¹

First recorded in 1940–45

Example Sentences

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

“Life loves carbon 12,” Green says.

From Scientific American

“If all the methane in this tube is carbon 12, we just increased our CoLD level by one.”

From Scientific American

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

From Seattle Times

Scientists who study cosmic rays used to think that these particles arrived in a relatively constant barrage, meaning that the ratio of carbon 14 to carbon 12 in the atmosphere has largely remained steady over time.

From Seattle Times