This entry contributed by Dana Romero
In the early 1920s, Ernest Rutherford Eric Weisstein's World of Biography investigated atomic structure by directing beams of alpha particles (which he already knew were positively charged helium ions) at foils made of different metals and counting the number of particles scattered in different directions (Rutherford scattering). Although most passed through undeflected, many were deflected by several degrees, some almost backwards. From this, he concluded that the atom consisted of a small but massive, positively charged core, which he called the nucleus, and which was surrounded by a cloud or swarm of electrons circling it, all being held together under the attraction of the Coulomb electric force.
With refinements from modern quantum mechanics and quantum electrodynamics, Rutherford's model essentially remains the model of atomic structure used today.
Bohr Model, Plum Pudding Model, Rutherford Scattering, Sommerfeld Model
References
Eisberg, R. and Resnick, R. "Rutherford's Model." §4-2 in Quantum Physics of Atoms, Molecules, Solids, Nuclei, and Particles, 2nd ed. New York: Wiley, pp. 90-95, 1985.
Gamow, G. Biography of Physics. New York: Harper and Row, 1961.
