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Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Dibya Ranjan Panda posted an Question
December 29, 2019 • 14:32 pm
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15 points
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.