1. Avogadro's Number

* Avogadro's number is a fundamental constant in chemistry: 6.022 x 10²³ atoms/mol. This means that one mole of any substance contains 6.022 x 10²³ particles (atoms, molecules, etc.).

2. Calculation

To find the number of atoms in 6.21 mol of Mg, use the following steps:

* Multiply the moles of Mg by Avogadro's number:

6.21 mol Mg × (6.022 x 10²³ atoms/mol) = 3.74 x 10²⁴ atoms of Mg

Therefore, there are approximately 3.74 x 10²⁴ atoms of magnesium in 6.21 mol of Mg.