Science, Tech, Math › Science Law of Multiple Proportions Definition - Chemistry Glossary Share Flipboard Email Print Westend61 / Getty Images Science Chemistry Chemical Laws Basics Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. 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. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated February 04, 2019 The Law of Multiple Proportions states that when elements combine, they do so in the ratio of small whole numbers (assuming they have the same type of chemical bonds). Also Known As: Dalton's Law, though that term usually refers to his law of partial pressure Examples: carbon and oxygen react to form CO or CO2, but not CO1.6