Mole
MCAT glossary · Chemical & Physical Foundations of Biological Systems
Definition
The amount of substance containing Avogadro's number of entities (6.022× 10^2^3).
Mole in plain English
Atoms and molecules are so unimaginably tiny that counting them one by one is hopeless, so chemists bundle them into a standard 'counting unit' called the mole — just like 'a dozen' always means 12, 'a mole' always means a fixed huge number. That number is Avogadro's number, about 6.022×10^23 particles. Because that specific count conveniently connects the mass you can weigh on a scale to the number of atoms involved, the mole is the bridge chemists use to turn grams into particle counts. So saying 'one mole of water' just means a specific, enormous, exact number of water molecules — a chemist's version of saying 'a dozen eggs.'
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