Dolphins. Paperclips. Monster trucks. What do these have in common? They, like all matter, are composed of particles called atoms.

What are atoms? Well, although the word ‘atom’ comes from a Greek word that means “indivisible,” we now know that atoms themselves are made of smaller parts called subatomic particles - namely, electrons, protons and neutrons. This is the basis of Atomic Theory, first stated by John Dalton, an English scientist, in the early 1800s.

John Dalton didn’t specifically focus on dolphins or paperclips (and certainly not monster trucks as they were yet to be invented.) But he did propose that all matter is made of atoms, that a chemical reaction is a rearrangement of these atoms and that compounds are formed by a combination of two or more different kinds of atoms.