[danmatts]

Hi I an trying to learn more about isotopes but I cant seem to find the information I want on google. I have a few straight forward questions (hopefully straight forward):

1: How many isotopes does each element have, how do you know how many each has?
2: Why do they all have a different number of isotopes/ why don't they all have the same amount?
3: Why do they have the amount of isotopes that they do/ what makes a certain element have a certain amount of isotopes?
4: Why do elements have isotopes/ what are they good for, what do they do?

Obviously I know nothing about isotopes but id really like to learn! Any other info that I should know or is just interesting please fill me in. Thanks!

[AWK]

Complete tables of natural and artificial isotopes can be easily find by google,
eg:
http://www.ciaaw.org/isotopic-abundances.htm
http://nucleardata.nuclear.lu.se/toi/

 Other questions have only one explanation so far - stability of nuclei.

[Enthalpy]

I've never read a working and reasonably simple theory that predicts whether a given nucleus is stable or not, so I suspect humans have none up to now.

What works :
- Even numbers of neutrons or protons are more stable.
- About as many neutrons as protons is more stable, but the proportion of neutrons increases with the atomic number.

That's all more or less... For instance, the "magic numbers" of protons or neutrons aren't very satisfactory. And unfortunately, this won't tell you a number of isotopes for a given element.

This is research presently, both to observe nuclei and to model them.

[Babcock_Hall]

With respect to 4, there is a journal of isotopes:  http://www.tws.org.cn/EN/volumn/current.shtml

Recently there was an article in Chemistry and Engineering news about the use of deuterium in drugs.  The Economist had an article on this subject about a year ago.