Science, Tech, Math › Science John Dalton's Atomic Theory Share Flipboard Email Print John Dalton - British physicist and chemist. Charles Turner, 1834 Science Chemistry Famous Chemists Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Anne Marie Helmenstine, Ph.D. Facebook Twitter Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. Learn about our Editorial Process Updated on September 05, 2019 You may take it for granted that matter is made up of atoms, but what we consider common knowledge was unknown until relatively recently in human history. Most science historians credit John Dalton, a British physicist, chemist, and meteorologist, with the development of modern atomic theory. Early Theories While the ancient Greeks believed atoms made matter, they disagreed on what atoms were. Democritus recorded that Leucippus believed atoms to be small, indestructible bodies that could combine to change properties of matter. Aristotle believed elements each had their own special "essence," but he did not think the properties extended down to tiny, invisible particles. No one really questioned Aristotle's theory, since tools did not exist to examine matter in detail. Along Comes Dalton So, it wasn't until the 19th century that scientists conducted experiments on the nature of matter. Dalton's experiments focused on gases -- their properties, what happened when they were combined, and the similarities and differences between different types of gases. What he learned led him to propose several laws, which are known collectively as Dalton's Atomic Theory or Dalton's Laws: Atoms are small, chemically indestructible particles of matter. Elements consist of atoms. Atoms of an element share common properties. Atoms of different elements have different properties and different atomic weights. Atoms that interact with each other obey the Law of Conservation of Mass. Essentially, this law states the number and kinds of atoms that react are equal to the number and kinds of atoms in the products of a chemical reaction. Atoms that combine with each other obey the Law of Multiple Proportions. In other words, when elements combine, the ratio in which the atoms combine can be expressed as a ratio of whole numbers. Dalton is also known for proposing gas laws (Dalton's Law of Partial Pressures) and explaining color blindness. Not all of his scientific experiments could be called successful. For example, some believe the stroke he suffered might have resulted from research using himself as a subject, in which he poked himself in the ear with a sharp stick to “investigate the humours that move inside of my cranium.” Sources Grossman, M. I. (2014). "John Dalton and the London atomists: William and Bryan Higgins, William Austin, and new Daltonian doubts about the origin of the atomic theory." Notes and Records. 68 (4): 339–356. doi:10.1098/rsnr.2014.0025 Levere, Trevor (2001). Transforming Matter: A History of Chemistry from Alchemy to the Buckyball. Baltimore, Maryland: The Johns Hopkins University Press. pp. 84–86. ISBN 978-0-8018-6610-4. Rocke, Alan J. (2005). "In Search of El Dorado: John Dalton and the Origins of the Atomic Theory." Social Research. 72 (1): 125–158. JSTOR 40972005 Cite this Article Format mla apa chicago Your Citation Helmenstine, Anne Marie, Ph.D. "John Dalton's Atomic Theory." ThoughtCo, Feb. 16, 2021, thoughtco.com/john-daltons-atomic-model-607777. Helmenstine, Anne Marie, Ph.D. (2021, February 16). John Dalton's Atomic Theory. Retrieved from https://www.thoughtco.com/john-daltons-atomic-model-607777 Helmenstine, Anne Marie, Ph.D. "John Dalton's Atomic Theory." ThoughtCo. https://www.thoughtco.com/john-daltons-atomic-model-607777 (accessed January 29, 2023). copy citation