atoms

[biotechie12]

hi.. i would like to know why C-12 was used as a reference for measuring atomic mass, other than being the most abundant isotope of carbon.. if any of u know the reason please let me know

[CaptainPanic]

Wikipedia says:

 

In the early twentieth century, up until the 1960s chemists and physicists used two different atomic mass scales. The chemists used a scale such that the natural mixture of oxygen isotopes had an atomic mass 16, while the physicists assigned the same number 16 to the atomic mass of the most common oxygen isotope (containing eight protons and eight neutrons). However, 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.

Does that answer the question?

[John Cuthber]

Carbon forms a lot of compounds with other elements and so it's relatively easy to compare the mass of those elements to that of carbon.

[ewmon]

Carbon forms a lot of compounds with other elements and so it's relatively easy to compare the mass of those elements to that of carbon.

I would agree. Yet, it seems logically/mathematically more suitable to use hydrogen as the "unit" (ie, the smallest whole number), and hydrogen seems as common as carbon as a molecular component.

[insane_alien]

yes, but a hydrogen is essentially an unbound proton. This prevents a lot of other atoms deviate a fair amount from integer values. carbon allows a larger number to be close to integer values.

[biotechie12]

Wikipedia says:

 

 

Does that answer the question?

 

yes thank u very much!

[rktpro]

Earlier, oxygen was used. But then they tend to go with c-12.