Avogadro’s Number (Nₐ)
It is the number of atoms, ions, or molecules in one mole of a substance.
Visual Weight Demonstration
Carbon Example
Avogadro’s number of carbon-12 atoms weighs exactly 12 grams.
A small lump of graphite weighing 12 g contains ~6.022 × 10²³ carbon atoms.
Demonstration: show students a piece of graphite or coal → “This small lump holds a number of atoms so large it would take millions of years to count.”
Copper Example
One mole of copper atoms weighs about 63.5 g (a chunk of copper metal about the size of a large coin).
This piece contains 6.022 × 10²³ copper atoms.
Teachers sometimes pass around a copper coin to let students feel the weight of a mole of atoms.
Water Example
18 mL of water (about a tablespoon) contains one mole of H₂O molecules.
That means just a spoonful of water holds ~6.022 × 10²³ molecules — a staggering number.
Why it Works
By tying Avogadro’s number to the weight of everyday objects (a coin, a spoon of water, a lump of carbon), students can feel the concept of a mole instead of only seeing a giant number on paper.
It demonstrates that, even though atoms are unimaginably small, Avogadro’s number brings them into the scale of grams, which we can handle.
✨ In short: The visual weight demonstration of Avogadro’s number uses real objects like a graphite lump, a coin of copper, or a spoonful of water to show that a mole — 6.022 × 10²³ particles — corresponds to something you can actually hold in your hand.