Video narration
When a reaction happens, do atoms disappear-or just change partners? Imagine matter as tiny beads. That's only a model, but it helps explain John Dalton's atomic theory: the idea that matter is made of tiny pieces called atoms. Dalton said each element has its own kind of atom, like a bead reserved for it. In his early picture, atoms were indivisible; later, science found they have smaller parts, so that idea needed an update. Now build a compound. Atoms don't join in a random handful; they combine in simple whole-number counts, like different beads making a fixed group. Different groups form different substances. Here's the flip: in an ordinary chemical reaction, atoms don't vanish. They rearrange into new groups. So, do they disappear? No. In Dalton's model, every atom makes roll call-beads simply find new groups.