1. Thomson's Plum Pudding Model: In the late 1800s, J.J. Thomson proposed that atoms were made up of a positively charged "pudding" with negatively charged electrons scattered throughout. This model was based on his discovery of electrons.
2. Rutherford's Nuclear Model: In 1911, Ernest Rutherford conducted the gold foil experiment and discovered that atoms had a small, dense, positively charged nucleus at the center, surrounded by negatively charged electrons. This model formed the basis of modern atomic theory.
3. Bohr's Planetary Model: In 1913, Niels Bohr proposed that electrons moved in fixed orbits around the nucleus, similar to the way planets orbit the sun. He also suggested that electrons could only move between these orbits by absorbing or emitting energy.
4. Wave Mechanical Model: In the late 1920s, Erwin Schrödinger and Werner Heisenberg developed the wave mechanical model, which proposed that electrons do not follow fixed orbits but instead exist in a probability cloud around the nucleus. This model is based on the idea of wave-particle duality.
5. Quantum Field Theory: In the mid-20th century, physicists developed quantum field theory, which describes subatomic particles as different excitations of underlying quantum fields. This theory is more complex and abstract, but it is able to accurately predict the behavior of subatomic particles.
6. Modern Developments: Modern atomic theory includes advancements such as the discovery of more subatomic particles beyond electrons, protons, and neutrons, as well as exploration into the behavior of antimatter and dark matter. Scientists continue to refine the models of the atom in order to better understand the nature of matter and energy.
Describe the changes that have happened to the model of the atom over time. (6)
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