The History of the Atomic Theory By PatrickJones 442 BCE Democritus Democritus posed the thought that all matter was composed of minuscule, indivisible, indestructible particles called the "atomos". He was a philosopher, so he did not provide any experimentation or empirical evidence to substantiate his claims. Period: Jan 1, 1803 to Dec 31, 1803 John Dalton
