I need help with a simple chemistry question.?

Question

It's actually supposed to be quite simple, but I've been searching everywhere for the past hour and I couldn't find anything exact on it. How do I calculate the abundance of isotopes? I would really appreciate it if someone responded. Thank you.

Answer 1

look at a complete mendeleev table which gives you the relative abundance of elements. There are isotopes existing not in the nature
or look in wilkipedia ex for hydrogen the isotope 1 H has an abundance of 99.98% ,the remaining is 2H 0.0002% and a tiny fraction of radioactive 3H formed by cosmic rays