what are the meaning of "angstrom," "coulomb," and "isotopes"?

Answer 1

Angstrom - a measure of distance on the atomic scale (ie: very very small)

Coulomb - A measure of charge - the amount of electricity transported by a current of one ampere flowing for one second.

Isotope - A modified atom that has more or less neutrons than a normal atom. So it keeps its molecular properties, but may be more or less stable (and bigger or smaller) than that normal atom.

Answer 2

uof... got it. For definitions of ALL units of measurement, try the following link. It's quite interesting.