| Particle | Charge | Relative mass | Where |
|---|---|---|---|
| 🔴 Proton | +1 | 1 | nucleus |
| ⚪ Neutron | 0 | 1 | nucleus |
| 🔵 Electron | −1 | 1/1836 (tiny) | around the nucleus in shells |
If an atom were the size of a football stadium, the nucleus would be about the size of a pea on the centre spot, yet it holds over 99.9% of the atom’s mass. Atoms are mostly empty space!