The atom



Although the Greek philosopher Democritus first suggested the idea of the atom in roughly two-and-a-half thousand years ago, it wasn’t until the beginning of the 19th century that people started taking it seriously.  This video summarises the basic picture of the atom which was developed as a result of a number of experiments in the 19th and early 20th centuries, and which will help us to describe much of the remainder of this topic.

Key Words

neutron, atomic number, mass number, radius, isotope, atom, nucleus, proton, electron