1. Dalton's Billiard Ball Model (~1803)
Dalton envisioned atoms as solid, indestructible spheres. This foundational theory introduced the atom as a fundamental, unbreakable unit of matter.
Interaction: Drag to rotate the model and use the controls below to explore its properties.
2. Thomson's Plum Pudding Model (~1897)
J.J. Thomson embedded negatively-charged electrons within a positive sphere. This was the first model to include subatomic particles, suggesting an internal atomic structure.
Interaction: Drag to rotate, and experiment with the electron properties using the controls.
3. Rutherford's Nuclear Model (~1911)
Rutherford's gold foil experiment revealed a tiny, dense nucleus. His model placed electrons in orbit around this central positive charge, showing the atom is mostly empty space.
Interaction: Rotate and zoom. Use the simulation platform to visualize the famous gold foil experiment.
4. Bohr's Planetary Model (~1913)
Niels Bohr proposed that electrons exist in quantized energy levels or "shells." This model successfully explained atomic emission spectra, a key piece of experimental evidence.
Interaction: Animate electron energy transitions and see how they correspond to photon emission.
5. Quantum Mechanical Model (Current)
The modern model treats electrons as waves, described by probability regions called orbitals. The "electron cloud" is a map of these probabilities, with distinct shapes (s, p, d, f).
Interaction: Explore the shapes of different atomic orbitals and their combinations.