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Dibya Ranjan Panda posted an Question
December 29, 2019 • 14:32 pm 15 points
  • IIT JAM
  • Chemistry (CY)

Why atomic mass is always measured as 1/12th of mass of carbon atom.

why atomic mass is always measured as 1/12th of mass of carbon atom.

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    Eduncle best-answer

    Dear Dibya Ranjan,

    Greetings!

    Here is the solution of your query.

    Carbon-12 is the standard while measuring the atomic masses. Because no other nuclides other than carbon-12 have exactly whole-number masses in this scale. This is due to two factors: the different mass of neutrons and protons acting to change the total mass in nuclides with proton/neutron ratios other than the 1:1 ratio of carbon-12; and an exact whole-number will not be located if there exists a loss/gain of mass to difference in mean binding energy relative to the mean binding energy for carbon-12.

    Oxygen was used as a standard for quite some time, but the results seem to be different in certain experiments. This was because oxygen-17 and oxygen-18 are also present in natural oxygen this led to 2 different tables of atomic mass. The unified scale based on carbon-12, 12C, met the physicists' need to base the scale on a pure isotope while being numerically close to the chemists' scale.

    Thank you for asking your query.

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