Science, Tech, Math › Science The Most Basic Unit of Matter: The Atom Share Flipboard Email Print Science Photo Library - ANDRZEJ WOJCICKI / Getty Images Science Chemistry Basics Chemical Laws 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 January 09, 2020 The basic unit of all matter is the atom. The atom is the smallest unit of matter that can't be divided using any chemical means and the building block that has unique properties. In other words, an atom of each element is different from an atom of any other element. However, even the atom can be broken into smaller pieces, called quarks. Structure of the Atom An atom is the smallest unit of an element. There are 3 parts of an atom: Proton: positive electrical charge, found in the nucleus of an atomNeutron: neutral or no electrical charge, found in the nucleus of an atomElectron: negative electrical charge, found circling the nucleus The size of the proton and neutron are similar, while the size (mass) of the electron is much, much smaller. The electrical charge of the proton and electron are exactly equal to each other, just opposite to each other. The proton and electron attract each other. Neither the proton nor the electron is attracted or repelled by the neutron. Atoms Consist of Subatomic Particles Each proton and neutron consist of even smaller particles called quarks. The quarks are held together by particles called gluons. An electron is a different type of particle, called a lepton. Proton: consists of 2 up quarks and 1 down quarkNeutron: consists of 2 down quarks and 1 up quarkElectron: is a lepton There are other subatomic particles, too. So, at the subatomic level, it's difficult to identify a single particle that could be called the basic building block of matter. You could say quarks and leptons are the basic building blocks of the matter if you like.