Science, Tech, Math › Science Element Symbol Definition in Chemistry Some symbols have changed over time Share Flipboard Email Print duntaro / 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 September 30, 2019 In chemistry, an element symbol usually refers to the one- or two-letter abbreviation for a chemical element, though the term also can be applied to the alchemical symbols. Key Takeaways: Element Symbol Definition An element symbol is a one- or two-letter abbreviation for a chemical element name.When a symbol consists of two letters, the first letter is always capitalized, while the second letter is lowercase.Element symbols also can refer to alchemy symbols for the elements or to the symbols used to describe isotopes. Examples Examples of modern element symbols include H for hydrogen, He for helium, and Ca for calcium. The first letter of an element symbol is capitalized, while the second letter is lowercase. An example of a deprecated element symbol is Cb for columbium, the former name of the element niobium, or Nb. However, some elements retain their old symbols when they change names. For example, Ag is the element symbol for silver, which was once called argentum. Sources Fontani, Marco; Costa, Mariagrazia; and Orna, Mary Virginia. "The Lost Elements: The Periodic Table's Shadow Side." Oxford University Press.Leal, João P. "The Forgotten Names of Chemical Elements." Foundations of Science.Wieser, Michael E., et al. "Atomic Weights of the Elements 2011." IUPAC Technical Report.