Rutherford's scattering experiment showed that atoms consist mostly of empty space, with a positively charged nucleus at the center. His experiments provided the first working model of atomic structure based on observation. Rutherford’s atom has a planetary structure, with negatively charged electrons orbiting around a positively charged nucleus and a large amount of empty space between the two.Continue Reading
Atomic models remained mostly speculative until 1911 when Ernest Rutherford proposed his model using experimental data from scattering experiments conducted by Hans Geiger and Ernest Marsden under Rutherford’s direction. The experiment used alpha particles (helium ions) directed toward a thin gold foil target. They observed that most of the positively charged alpha particles passed straight through the foil. Some of the alpha particles showed small deflections of just a few degrees as they passed through, but a few showed a large deflection angle, greater than 90 degrees. Based on these results Rutherford proposed that atoms contain a small, densely packed nucleus with a positive charge and that electrons, considerably smaller, orbited the nucleus.
Based on Rutherford’s equations, physicists had their first solid evidence of the size of the nucleus relative to the size of an atom itself. Subsequent experiments would refine these numbers. Neils Bohr refined Rutherford’s planetary model and countered objections to the orbiting electrons by creating energy shells and describing how energy moved from one shell to another and emitted light quanta to maintain a balance. While quantum physics explains the energy states more accurately, Rutherford’s nucleus still persists, albeit in a wildly different way than he might have imagined.Learn more about Physics