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Actually, according to WebElements, there is one, and only one, naturally occuring thorium isot ope: Th232. So, apparently, naturally occuring thorium is not a mix of isotopes, but one isotope.

There are other "man-made" radioisotopes. A couple have fairly long half-lifes (in the thousands of years). The longest (Th230) is about 75,400 years. But that's a mere blink of the eye, in cosmological and geological terms, which explains why there's only a single naturally occuring isotope (all others have long since decayed into something else). The probability of finding a significant number of "natural" atoms in the entire earth of any isotope of thorium other than Th232 is probably very, very small (but nonzero).

Actually, according to WebElements, there is one, and only one, naturally occuring thorium isot ope: Th232. So, apparently, naturally occuring thorium is not a mix of isotopes, but one isotope.

There are other "man-made" radioisotopes. A couple have fairly long half-lifes (in the thousands of years). The longest (Th230) is about 75,400 years. But that's a mere blink of the eye, in cosmological and geological terms, which explains why there's only a single naturally occuring isotope (all others have long since decayed into something else). The probability of finding a significant number of "natural" atoms in the entire earth of any isotope of thorium other than Th232 is probably very, very small (but nonzero).

Here's a thrid periodic table at:
http://ww w.shef.ac.uk/chemistry/web-elements/nofr-key/perio dic-table.html

This site includes MUCH information on electron configuration, physical properties, history, and much more. What's interesting are the humorous cartoons and .au files to educate the correct pronounciation of the element name.


~afniv
"Man könnte froh sein, wenn die Luft so rein wäre wie das Bier"
"We could be happy if the air was as pure as the beer"