A Dozen Atoms

What this book is about

The place where most people give up on HSC chemistry is not a hard experiment and not an expensive instrument. It is a counting word. The word is mole. It sounds foreign, it looks solemn, and the definition in the textbook is written in a way that leaves you certain something is being kept from you.

Nothing is being kept from you. A mole is the name of a number, exactly as a dozen is the name of twelve. A dozen for counting eggs; a mole for counting atoms. The whole work of this book is to take that one line in hand and walk eighty-eight pages with it — and to find, along the way, that the sack of fertiliser, the lime kiln and the examination paper all come out of that same one line.

No formula falls from the sky. Wherever a formula is needed it is born on that page — first in numbers, then in letters. There is nothing in this book to memorise.

What is inside

• The rice jar, how small an atom is, and how big Avogadro's number really is
• Mass as ratio: the two pans of a balance, and why carbon-12 is the standard
• What a formula tells you — percentage composition, urea in the paddy field, empirical

against molecular formulas, and the extra gift of gases

• An equation as a ledger: counting atoms on both sides, and coefficients as mole ratios
• How much gives how much — four steps, limestone to lime, and what runs out first in a

factory

• Those who learned to count — Lavoisier's balance, Dalton's table, Avogadro's guess and

fifty years of silence, Karlsruhe 1860, and Perrin measuring the number

• Two experiments to try, every rule in one place, exercises, a glossary and a quiz