Boxi Learn › Chemistry › Stage 3 · Structure and Evidence
A mole is a number, like a dozen
CHEM-1 Atoms are rearranged, never lostX-3 Look from another side
What many people think
A mole is an amount of mass, so one mole of any substance weighs the same.
The idea
A mole is a fixed count of particles, 6.02 × 10²³; a mole of magnesium weighs twice a mole of carbon because each magnesium atom is twice as heavy.
Explain it
A friend says 1 mol of copper and 1 mol of sulfur must weigh the same because “a mole is a mole.” Explain what is the same and what is different, using the balance.
Try at home
On a kitchen scale, weigh 100 grains of rice and then 100 dried beans. Same count, different mass. Use the 100-grain mass to work out how many rice grains are in a 1 kg bag, without counting them. Chemists count atoms the same way.