The mole and Avogadro constant

The key idea

The mole connects the microscopic world of atoms and molecules to measurable laboratory amounts. One mole contains exactly the Avogadro constant number of specified entities.

Why it matters

It is chemistry’s counting unit: like a dozen, but designed for unimaginably small objects.

A useful mental picture

It is chemistry’s counting unit: like a dozen, but designed for unimaginably small objects.