CHEMISTRY COMMUNITY

Why is the quantity of the mole based on a Carbon atom instead of elements like Oxygen or Nitrogen?

In the past there have been different standards set for the atomic scale, such as oxygen because its many bonding characteristics. However Oxygen has many isotopes that that vary in weight etc, so carbon 12 was chosen which as similar to the previous scale.

I am not completely sure why carbon was chosen but I assumed that it had something to do with the importance of carbon and it's relevance in life in general.

I'm not 100% sure, but I figured it was because carbon is essential to life - it is a main focus point in all forms of science and understanding it is necessary in the study of life and how the world works.

One mole is the number of atoms in exactly 12 g of carbon-12 because the atomic mass scale is defined by the mass of carbon-12. This means that one atomic mass unit is defined to be 1/12 of the mass of a carbon-12 atom. Therefore, the number of atoms in 12.0000...000 grams of carbon-12 is Avogadro's number, which is a mole.

I think it's because the atomic mass scale is also based on carbon-12, and that's because carbon-12 has a whole number mass unlike any other element on the periodic table.