Nuclear physics studies the nucleus of the atom. In 1911, the British scientist Ernest Rutherford explained that the mass of an atom is concentrated in its central part called the nucleus. Unstable nuclei decay and emit harmful radiations – this is radioactivity. This unit also covers nuclear fission and fusion, their uses and the nuclear reactor.
1. The Atom and Its Particles
| Scientist | Year | Contribution |
|---|---|---|
| Democritus (Greek philosopher) | 400 BCE | Matter is made up of tiny indestructible units called atoms |
| John Dalton | 1803 | Elements consist of atoms, which are identical in nature |
| J J Thomson | – | Discovered cathode rays, known as electrons |
| Goldstein | – | Discovered positive rays, named protons by Rutherford |
| Ernest Rutherford | 1911 | Mass of an atom is concentrated in the central nucleus |
| James Chadwick | 1932 | Discovered the chargeless particles called neutrons |