For example, copper and chlorine can form a green, crystalline solid with a mass ratio of 0.558 g chlorine to 1 g copper, as well as a brown crystalline solid with a mass ratio of 1.116 g chlorine to 1 g copper. The law of multiple proportions states that when two elements react to form more than one compound, a fixed mass of one element will react with masses of the other element in a ratio of small, whole numbers. For example, there are many compounds other than isooctane that also have a carbon-to-hydrogen mass ratio of 5.33:1.00.ĭalton also used data from Proust, as well as results from his own experiments, to formulate another interesting law. Dalton’s experiments with gases led to some of the earliest measurements of atomic masses and a concept of atomic structure and reactivity. The module then describes Thomson’s plum pudding model of the atom along with Rutherford’s gold foil experiment that resulted in the nuclear model of the atom. How did we get here Well, in terms of Atomic Chemistry, Hank takes us on a tour of the folks that were part of the long chain of other folks who helped us g. This module takes readers through experiments with cathode ray tubes that led to the discovery of the first subatomic particle: the electron. That is, samples that have the same mass ratio are not necessarily the same substance. Looking for an engaging, student centered Atomic Theory Activity These History of the Atom Stations will have your students researching six pioneering. The 19th and early 20th centuries saw great advances in our understanding of the atom. Ernest Rutherfords gold foil experiment in 1911 led to the discovery of the atomic nucleus. It is worth noting that although all samples of a particular compound have the same mass ratio, the converse is not true in general. John Dalton proposed the first modern atomic theory in 1803.

History of atomic theory