Isotopes react in the same way, don’t they?

Chemical reactions are unaffected by the isotopic composition so the percentage of different isotopes of the same element in a substance would be the same as the percentage of each naturally occurring isotope.

Well, this is true on earth but it is not the case in space, deep space where the temperature is really low and the concentration of atoms very very small.

In effect, one isotope will become more reactive than the other.

Scientists have found that comet dust (collected in the stratosphere) contains a different isotopic composition of carbon and nitrogen to what would be found on earth.  The amazing thing is that this dust is, wait for it, older than our solar system – over 4.5 billion years old!

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There are fewer heavier carbon isotopes than would be expected and more nitrogen heavy isotopes than would be expected.

Oh, and the other amazing thing about this dust is that it contains complex organic molecules – showing that the molecules of life itself can form in the very cold regions of deep space.

This posting was adapted from an article in New Scientist magazine, 6th March 2004 on page 6, titled ‘Mystery particle floats in from depp space’.