How is Avogadro’s number used to compare amounts of atoms and molecules?

Avogadro’s number, defined as $6.02214076\times {10}^{23}$, serves as the fundamental constant for the mole, a standard unit used to measure large quantities of atoms, molecules, or other particles.123

Because this number of units is the same for any substance, it allows chemists to compare amounts of different materials on a macroscopic level. By using the mole, scientists can relate the number of particles to a measurable mass. For example, one mole of carbon-12 contains $6.02214076\times {10}^{23}$ atoms and has a mass of 12 grams, whereas one mole of oxygen contains the same number of atoms but has a mass of approximately 15.999 grams.2

This relationship enables the calculation of quantities in chemical reactions, as it provides a bridge between the count of individual particles and the mass of the substances involved. Additionally, Avogadro’s law further aids these comparisons by stating that equal volumes of different gases at the same temperature and pressure contain an equal number of molecules.214