Relative Atomic Mass 1u: Mass of Carbon-12 Atom & Oxygen-16 Atom

[cks]

1 u = 1/12 of the mass of a neutral carbon atom with nuclear charge 6 and mass number 12,

1 u = 1/12 * 12.000000 /NA * 0.001

where NA is avogadro's number.

I wonder is it that the scientists purposely make one mole of carbon-12 to be just 12.00000g?

I want to ask is it when the relative atomic mass of oxygen-16 is 15.99491, then the mass of the oxygen-16 atom is 15.99491 * 1u.?

 

[f95toli]

Well, Avogadro's number is, by definition, equal to the number of atoms in 12 gram of carbon-12.
So, yes, it is on purpose.