Video narration
What's actually inside an atom: a tiny solid ball, or something very different? Think of a school playground: a small group at the center, with open space around it. An atom has that same basic arrangement: a nucleus at the center, surrounded by a much larger region containing electrons. The nucleus holds protons, with positive charge, and neutrons, with no charge. Electrons have negative charge. They are not planets on neat circular tracks. They occupy an electron cloud-a region where they are likely to be found. Diagrams of this are simplified, not drawn to scale. The number of protons gives an atom its identity: it tells you which element it is. So, what's inside? Not a tiny solid ball. It's a tiny nucleus of protons and neutrons, surrounded by electrons. Most of the atom is empty space, while nearly all its mass sits in that tiny center.