John Dalton created Dalton's law, which states that the total pressure exerted by a mixture of non-reactive gases is equal to the sum of the partial pressures of individual gases. John Dalton also had an atomic theory which states that elements are made of small particles called atoms. Atoms of the same element have the same proporties and atoms of different elements have different proporties. Atoms can't be subdivided, created, or destroyed. Atoms of different elements combine in simple whole-number ratios to create compounds. In chemical reactions atoms are combined, separated or rearranged.