Chemistry help!

I can not find the official definition for the terms:

Percent Abundance

Relative Abundance

I have tried several book glossaries as searchs…I guess they by themselves don’t have any meaning, but I need this is a chemistry topic sense…any help?

I suspect you are referring to the relative/percent abundance of isotopes.

Relative abundance of a given isotope is the simply the proportion of that isotope in a naturally occurring mixture of isotopes (for that element).

Percent abundance is the relative abundance expressed as a percentage.

You can find isotopic abundances in the Handbook of Chemistry and Physics.

This website may help:

Your help was greatly appreciated…thanks