Why is isotope of carbon c-12 is used as standard unit for atomic mass and molecular mass
Why is isotope of carbon c-12 is used as standard unit for atomic mass and molecular mass
Atually, the choice is quite arbitary.
When you measure the mass of an object you compare its mass to an arbitrary unit mass, gr, ounce, pound, etc. It is like when you measure the length of an object you compare its length to an arbitrary length unit, cm, yard, ft, etc.
Before carbon was elected for this purpose, the atomic mass unity was based on hydrogen and later on oxygen.
In 1961 it was decided that the isotope C-12 should be the basis for atomic mass unity and mass 12 (exact) was conferred to it ARBITRARY!. Accordingly, 1/12 of the mass of carbon-12 is the atomic mass unity and it is arbitrary. This unit may be replaced in future to another one if the International Union of Pure and Applied Chemistry so decides.
Further, factors deciding selection of carbon include the fact that the isotope of Carbon with 6 protons and 6 neutrons in its nucleus (Carbon-12) was given a mass of exactly 12. It was a good choice, since it was in between the two previously used standards, and meant that nothing had to change too much. Plus, Carbon-12’s atomic mass could be measured particularly accurately compared to the other elements on the periodic table.
Atually, the choice is quite arbitary.
When you measure the mass of an object you compare its mass to an arbitrary unit mass, gr, ounce, pound, etc. It is like when you measure the length of an object you compare its length to an arbitrary length unit, cm, yard, ft, etc.
Before carbon was elected for this purpose, the atomic mass unity was based on hydrogen and later on oxygen.
In 1961 it was decided that the isotope C-12 should be the basis for atomic mass unity and mass 12 (exact) was conferred to it ARBITRARY!. Accordingly, 1/12 of the mass of carbon-12 is the atomic mass unity and it is arbitrary. This unit may be replaced in future to another one if the International Union of Pure and Applied Chemistry so decides.
Further, factors deciding selection of carbon include the fact that the isotope of Carbon with 6 protons and 6 neutrons in its nucleus (Carbon-12) was given a mass of exactly 12. It was a good choice, since it was in between the two previously used standards, and meant that nothing had to change too much. Plus, Carbon-12’s atomic mass could be measured particularly accurately compared to the other elements on the periodic table.
