Science, Tech, Math › Science What Is an Atom? Atom explanation and examples Share Flipboard Email Print Paper Boat Creative/Getty Images Science Chemistry Molecules Basics Chemical Laws 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 May 06, 2019 An atom is the basic unit of an element. An atom is a form of matter which may not be further broken down using any chemical means. A typical atom consists of protons, neutrons, and electrons. Atom Examples Any element listed on the periodic table consists of specific atoms. Hydrogen, helium, oxygen, and uranium are examples of types of atoms. What Are Not Atoms? Some matter is either smaller or larger than an atom. Examples of chemical species that are not typically considered atoms includes particles that are components of atoms: protons, neutrons, and electrons. Molecules and compounds consist of atoms but are not themselves atoms. Examples of molecules and compounds include salt (NaCl), water (H2O) and methanol (CH2OH). Electrically charged atoms are called ions. They are still types of atoms. Monoatomic ions include H+ and O2-. There are also molecular ions, which are not atoms (e.g., ozone, O3-). The Gray Area Between Atoms and Protons Would you consider a single unit of hydrogen to be an example of an atom? Keep in mind, most hydrogen "atoms" do not have a proton, neutron, and electron. Given that the number of protons determines the identity of an element, many scientists consider a single proton to be an atom of the element hydrogen.