Human understanding of the atom transformed across three centuries, moving from indivisible solid spheres to quantum fields held together by relativistic forces.
| Scientific Model | Active Era | Core Structural Hypothesis | Primary Point of Failure |
|---|---|---|---|
| Daltonian Sphere | 1803, 1897 | Indivisible, uniform, solid spheres of varying elemental mass. | Discovery of the electron via cathode ray experiments. |
| Rutherford Nuclear | 1911, 1913 | Dense, positively charged core surrounded by loose orbiting electrons. | Failed to explain why orbiting electrons did not radiate energy and collapse. |
| Bohr Planetary | 1913, 1926 | Quantized concentric orbits; radiation occurs only during orbital transitions. | Incapable of resolving multi-electron systems or wave mechanics. |
| Quantum Cloud Model | 1926, Present | Probabilistic 3D orbitals determined by Schrödinger wave equations. | Remains current; continuously refined by quantum chromodynamics. |
