ABSTRACT
The mystery of the atom and its true nature began to unravel in the late nineteenth century when the physicist J. J. Thompson (1856-1940) discovered within matter a negatively charged particle, which was named the electron. This led to a new way of visualising an atom. Instead of imagining it to be a solid sphere, Thompson visualised it as a mass of positive matter with negative electrons scattered throughout like plums in a suet pudding.
