1.1.4 The nature of the nucleus
You have now learned about the particles that make up atoms, protons, neutrons and electrons.
These are collectively termed subatomic particles and are summarised in Table 4.
| Electric charge | Notes | |
|---|---|---|
| Electron | −1 unit | In a neutral atom, number of electrons = number of protons |
| Nucleons | Mass number = number of nucleons | |
| Proton | +1 unit | Atomic number = total number of protons |
| Neutron | 0 | Isotopes of the same elements have different numbers of neutrons |
In the next sections you will find out how the nature of the nucleus and the nucleons within lead to radioactivity and the fission reactions that power nuclear reactors.