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Period: to
Development of the Atom
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John Dalton's Billiard Ball Model
Dalton rejected popular scientific stratgies and trusted his intuition through his experiments with atomic weight.
Flaw - Dalton did not account for any kind of charge in the atom
Extra Info - Proposed the "Rule of Greatest Simplicity" which states when atoms combine in one ratio, it must be presumed to be a binary one. -
Sir J.J. Thomson's "Raisin Bun" Model
Discovered that cathode rays could be deflected by both magnetic and electric fields, and possessed some sort of charged particle. This led to his theory of the electron, a negatively charged particle, which he assumed where embedded on the outside of the atom since cathode rays bent toward the positive plate. This model was proven false by Rutherford's scattering experiment, which suggested the majority majority of the mass was focussed in the nucleus. He taught Rutherford at Manchester. -
Ernest Rutherford's "Rutherford's Model"
-Rutherford directed a beam of alpha particles at a thin gold foil, expecting that all would pass through undeflected, but noticed that some were scattered and bounced back
-Proposed atoms had a nucleus containing the majority of the mass and a positive charge
Flaw - Did not discover what prevents electrons from being pulled into the nucleus by electrostatic attraction
- Rutherford was born in New Zealand and a boss rugby player -
Nuclear Model
Scientists sought to explain how electrons could behave within Rutherford'smodel. Some suggested that electrons would orbit around the nucleus like rings, such as Hantaro Nagaoka. . Scientists could not explain why the electrons would stay in orbit and not be drawn toward the centre by electrostatic atraction. Jean Baptiste Perrin claims he was the first to suggest this model, backin 1901, but did not have sufficient proof. -
The Niels Bohr Model
Studied atomic spectra and discovered that certain gases would emit/release only specific wavelengths of EMR. Hypothesized that these differences were caused by the difference in energy required to move an electron up or down an energy level (supporting quantization) for a specific element. The Heisenberg uncertainty principle, which suggests electrons could not have known orbits and locations simultaneously, seems to disprove the theory. Similar to planetary orbits, but with electric forces.
