John+Dalton

John Dalton [|http://www.rsc.org/chemsoc/timeline//pages/1803.html] [] Summarize his theory of the atom. There are multiple parts to his model of the atom. Explain each and include visuals to help us understand each part.

Daltons Model of an Atom

All matter is made up of atoms Atoms cannot be made or destroyed All atoms of the same element are identical Different elements have different types of atoms Chemical reactions happens when atoms are rearranged Compounds are formed from atoms of the made up elements

Atoms are made up of three types of particles. Protons, electrons, and neutrons. Protons have a positive charge and electrons have a negative charge.

In 1803 Dalton noted that oxygen and carbon combined to make two compounds. Of course, each had its own particular weight ratio of oxygen to carbon (1.33:1 and 2.66:1), but also, for the same amount of carbon, one had exactly twice as much oxygen as the other. This led him to propose the Law of Simple Multiple Proportions In an attempt to explain how and why elements would combine with one another in fixed ratios and sometimes also in multiples of those ratios, Dalton formulated his atomic theory. Dalton's theory was different in that it had the weight of careful chemical measurements behind it. It wasn't just a philosophical statement that there are atoms because there must be atoms. His atomic theory, stated that elements consisted of tiny particles called atoms. He said that the reason an element is pure is because all atoms of an element were identical and that in particular they had the same mass. He also said that the reason elements differed from one another was that atoms of each element were different from one another; in particular, they had different masses. He also said that compounds consisted of atoms of different elements combined together.