Question

How does the mole relate to atoms, molecules and ions?

Answer 1

A mole is simply a quantity of `6.022xx10^23` of anything. We can have a mole of atoms, molecules, ions... or elephants.

One mole of atoms of an element has a mass equivalent to the 'mass number' (now sometimes called 'nucleon number') of that element, e.g. 1 mole of `""_6^12C` has a mass of `12` `g`.

Explanation:

Technically it's slightly more complex than the answer above, because different isotopes have different mass numbers and abundances.

Carbon is mostly `""_6^12C`, with very small amounts of `""_6^13C` and `""_6^14C`, so the relative atomic mass of naturally occurring carbon is very close to `12` gmol^-1#.

On the other hand, naturally occurring chlorine is about `3/4` `""_17^35Cl` and about `1/4` `""_17^37Cl`, so the relative atomic mass of naturally occurring `Cl` is about `35.5`.