How atomic theory developed: from Dalton to the electron cloud

Our model of the atom was built step by step from experimental evidence. John Dalton proposed that all matter is made of tiny atoms, that atoms of the same element are alike, and that compounds form when atoms combine in whole-number ratios. J. J. Thomson discovered the negatively charged electron using cathode rays, showing atoms have smaller parts. Ernest Rutherford's gold foil experiment showed that an atom's positive charge and most of its mass are packed into a tiny, dense nucleus, with the rest mostly empty space. Niels Bohr proposed that electrons occupy fixed energy levels around the nucleus. Heisenberg's uncertainty principle showed that an electron's exact position and momentum cannot both be known at once, which led to today's model of electrons in a probability cloud.

This explanation is AI-generated and can occasionally be wrong. 🚩 Report