carbon 12


: an isotope of carbon of mass number 12 that is the most abundant carbon isotope and is used as a standard for measurements of atomic weight

Examples of carbon 12 in a Sentence

Recent Examples on the Web Most carbon exists in the stable form of carbon 12. James Shreeve, Discover Magazine, 11 Nov. 2019 Scientists can look at the amount of carbon 12 and--based on the ratio-- deduce how much carbon 14 was originally present. James Shreeve, Discover Magazine, 11 Nov. 2019 Measuring the extent to which multiple carbon 13 atoms (a rare, stable form of carbon with an extra neutron) replace carbon 12 (the most common form of carbon) in a particular molecule, for instance, can tell researchers about the temperature when the compound formed. Clara Moskowitz, Scientific American, 15 June 2023 Carbon has two stable isotopes, measured as either carbon 12 or carbon 13. Ashley Strickland, CNN, 17 Jan. 2022 But if Perseverance’s sample is found to contain not only methane but methane rich in an isotope called carbon 12, that could change. Jonathan O'Callaghan, Scientific American, 10 Nov. 2021 So researchers compare the amount of carbon 14 with the levels of carbon 12 and carbon 13 to determine how much time has passed since an organism perished. Scott Hershberger, Scientific American, 4 Aug. 2020 Chemically, carbon 14 behaves exactly like its stable siblings (carbon 12 and carbon 13), allowing plants to absorb it during photosynthesis and then pass it up the food chain. Scott Hershberger, Scientific American, 4 Aug. 2020 By controlling the magnetic field and other conditions inside the cannon, the researchers cause the carbon 14 atoms to veer away from the carbon 12 atoms and other elements. Carl Zimmer, The Atlantic, 20 Mar. 2020

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'carbon 12.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1936, in the meaning defined above

Time Traveler
The first known use of carbon 12 was in 1936

Dictionary Entries Near carbon 12

Cite this Entry

“Carbon 12.” Dictionary, Merriam-Webster, Accessed 29 May. 2024.

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