Experiments with gases that first became possible at the turn of the nineteenth century led John Dalton in 1803 to propose a modern theory of the atom based on the following assumptions. 1. Matter is made up of atoms that are indivisible and indestructible. ... All atoms of an element are identical. read more
Atomic Theories & Gas Experiments John Dalton Atomic Theory The Premise: atoms of different elements could be distinguished by differences in their weights. The fundamental difference of each atom is the atomic mass 1. All matter is composed of atoms. read more
Modern Atomic Theory (John Dalton) Experiments with gases that first became possible at the turn of the nineteenth century led John Dalton in 1803 to propose a modern theory of the atom based on the following assumptions. 1. Matter is made up of atoms that are indivisible and indestructible. read more
Best Answer: John Dalton (1766-1844) developed the first useful atomic theory of matter around 1803. In the course of his studies on meteorology, Dalton concluded that evaporated water exists in air as an independent gas. read more