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

Question

Naomi Aronson · Accepted Answer

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#.

Because different isotopes have distinct mass numbers and abundances, the answer is technically a little more complicated than it was in the previous paragraph. 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#.

Wyatt Atkins · Answer

undefined The mole is a unit of measurement used in chemistry to express amounts of substances. It relates to atoms, molecules, and ions by providing a way to count and compare their quantities in chemical reactions. One mole of any substance contains Avogadro's number of particles, which is approximately $6.022 \times 10^{23}$. This means one mole of atoms, molecules, or ions contains the same number of particles regardless of the element or compound.