Here's how to calculate the number of moles of magnesium atoms in 100 grams of magnesium:

1. Find the molar mass of magnesium:

* The molar mass of magnesium (Mg) is 24.305 g/mol. This means that one mole of magnesium weighs 24.305 grams.

2. Use the formula:

* Moles = Mass / Molar Mass

3. Plug in the values:

* Moles = 100 g / 24.305 g/mol

* Moles ≈ 4.11 moles

Therefore, there are approximately 4.11 moles of magnesium atoms in 100 grams of magnesium.