Nuclear Physics Question

[Atlantic]

Does anyone know why certain isotopes are put in the periodic table? Do they put the most stable ones or the ones with least ammount of neutrans (unstable).

 

Another question: What forms of carbon are radioactive? I know that Carbon 14, Carbon 11, and carbon 32 are radioactive, which others are, or all isotopes are radioactive.

[VendingMenace]

[qutoe]

Does anyone know why certain isotopes are put in the periodic table?

 

They do not really put any isotopes on a standard periodic table, at least that i am aware of. What exactly do you mean by this?

[Atlantic]

ok answer this: Why is Carbon 12 on the periodic table, while carbon 11, carbon 14, carbon 32 etc aren't. What is so special about Carbon 12 that they put it on the periodic table instead of other of its isotopes.

 

I don't think the nucleus is very stable in that either, or is that as stable as its gonna be?

[blike]

Atlantic said in post #3 :

ok answer this: Why is Carbon 12 on the periodic table, while carbon 11, carbon 14, carbon 32 etc aren't. What is so special about Carbon 12 that they put it on the periodic table instead of other of its isotopes.

 

I don't think the nucleus is very stable in that either, or is that as stable as its gonna be?

 

The atomic mass on the periodic table does include data from the isotopes. The atomic mass on an accurate periodic table sum of all the isotopes * relative natural abundance.

 

That is, carbon 12 has an atomic mass of 12.000000000, and has a natural abundance of 98.90%.

 

Carbon 13 has an atomic mass of 13.003354826 and has an abundance of 1.10%.

 

(12.0 * .9890) = 11.868

(13.003354826 * .0110) = .143036

 

Sum them and you get roughly 12.011...most periodic tables have 12.0107 for carbons mass. They are calculated to a higher precision than what I just did, but you get the general idea.

[swansont]

Atlantic said in post #1 :

Does anyone know why certain isotopes are put in the periodic table? Do they put the most stable ones or the ones with least ammount of neutrans (unstable).

 

Another question: What forms of carbon are radioactive? I know that Carbon 14, Carbon 11, and carbon 32 are radioactive, which others are, or all isotopes are radioactive.

 

On the periodic table it's the average mass, wieghted by the abundance, as noted. For atoms with no stable isotopes, it's the longest-lived isotope that's represented, and the mass number is given (total number of protons+neutrons).

 

C-12 and C-13 are stable. All other isotopes are unstable. Don't hold your breath trying to find any C-32, though - it's very far from the line of stability, so I doubt it's ever been synthesized.