Here's where chemistry gets practical. Atoms are tiny - you can't count them one by one. So chemists invented the mole. One mole is 602,000,000,000,000,000,000,000 particles. That's 6.02 × 10²³ - Avogadro's number.
It's like a dozen, but for atoms. A dozen eggs is 12 eggs. A mole of eggs would be enough eggs to cover the entire Earth!
Why This Helps
With moles, we can convert between mass and number of particles. That's huge for calculations. It lets us measure things in grams but think in atoms.