Dalton's atomic theory
Chemistry gets atoms with distinct weights, and combining ratios make sense.
- When
- —
- Duration
- 5 years
- Known to
- ± 1 year
- Era
- Industrial, Holocene
John Dalton proposes from 1803 that each element consists of identical atoms with a characteristic weight, and that compounds form in fixed whole-number ratios. It explains why substances combine in the proportions they do, and gives chemists something to count. Atoms remained a useful fiction to many physicists until Einstein's 1905 analysis of Brownian motion and Perrin's experiments made them undeniable.