ABSTRACT
J. J. Thomson suggested that the atom consisted of a number of electrons immersed in a sphere of positive charge. For obvious reasons, this model is generally known as the 'plum pudding' model. A seductive alternative would be for the electrons to move in closed orbits around the nucleus - the 'sun and planet' model often used as a symbolic representation of the atom. Any attempt to construct a model of the atom must start from two experimental facts. First, the atom is electrically neutral. Second, it appears to contain electrons which are negatively charged and relatively light in mass compared with the atom itself. Between 1909 and 1912, Geiger and Marsden, two physicists working with Rutherford, carried out the first definitive experiments to probe the structure of the atom. Rutherford's nuclear model fitted exceptionally well with the experimental data accumulated from scattering experiments.
