The mass of one carbon-12 atom is 12 amu, but why is the atomic mass of carbon reported as 12.011 amu (instead of 12 amu exactly) on the periodic table?
2006-10-09 15:52:43 · 4 answers · asked by SuperCee 2 in Education & Reference ➔ Homework Help
So it 12.011 the avg of all isotopes?
2006-10-09 15:59:20 · update #1
Thanks everyone.
2006-10-09 16:07:11 · update #2
Because there are three isotopes of carbon C12,C13, and C14 having different atomic weights(as they have different neutron no.)The atom of carbon12 is most stable and therefore its at. wt. is taken as standard ie 12 amu.Other two atoms of carbon are present in traces and are mainly unstable(C14 is radioactive).
YES!According to in what numbers they are present.(C12 constitutes about 99% of all carbon atoms!)
2006-10-09 15:58:22 · answer #1 · answered by Saif 3 · 1⤊ 0⤋
This is because of all the isomers (i think that's the word). There are some carbon atoms that have 13 neutrons but still have 12 protons. This does not add a charge, but it does change the mass. The majority of carbon atoms are carbon 12, but there is like a less than 5% amount of carbon 13. Hence, when you average the two with the small amount of carbon 13 with the normal carbon 12 it comes to like 12.011 amu instead of 12amu
2006-10-09 23:34:41 · answer #2 · answered by Jamie J 3 · 0⤊ 0⤋
Yes the 12.011 is the average of Carbon's three isotopes.. 12, 13, 14
2006-10-09 23:00:39 · answer #3 · answered by Magnitudex 2 · 0⤊ 0⤋
Beacuse the 12 amu is only one isomer you can also have heavier or lighter carbons. Such as 13 carbons which actually has an amu of 13. The value of 12.11 is just an average. It is closer to 12 because 12 is by far the most common.
2006-10-09 23:05:35 · answer #4 · answered by Josh J 1 · 0⤊ 0⤋