Structure of the atom
Atoms are very small, they have a radius of around 1 Ă 10-10 metres.
The modern view of the atom is of a The central part of an atom. It contains protons and neutrons, and has most of the mass of the atom. The plural of nucleus is nuclei. containing Subatomic particle with a positive charge and a relative mass of 1. The relative charge of a proton is +1. and Uncharged subatomic particle, with a mass of 1 relative to a proton. The relative charge of a neutron is 0. with smaller electrons orbiting outside the nucleus.
The nucleus has a diameter of around 1 Ă 10-15 metres
Each particle has its own charge and its own mass.
| Relative charge | Relative mass | Found | |
| Proton | +1 | 1 | Inside the nucleus. |
| Neutron | 0 | 1 | Inside the nucleus. |
| Electron | -1 | 1/1840 (Close to 0) | Orbiting the nucleus. |
| Proton | |
| Relative charge | +1 |
| Relative mass | 1 |
| Found | Inside the nucleus. |
| Neutron | |
| Relative charge | 0 |
| Relative mass | 1 |
| Found | Inside the nucleus. |
| Electron | |
| Relative charge | -1 |
| Relative mass | 1/1840 (Close to 0) |
| Found | Orbiting the nucleus. |
Summary
- Atoms contain 3 types of particle: protons, neutrons and electrons.
- Protons and neutrons are found in the nucleus of an atom.
- Electrons orbit the nucleus.
A helium atom
There are two protons and two neutrons in the nucleus at the centre of the atom.
Two electrons orbit the nucleus.