Parts of an Atom

Atoms consist of three main particles: protons, neutrons, and electrons. Protons have a positive charge and are located inside the nucleus at the center of the atom. Each proton has a mass of 1 atomic mass unit (amu) and helps determine the atom's overall mass.

Neutrons sit alongside protons in the nucleus and have a neutral charge (no charge at all). Like protons, neutrons also have a mass of 1 amu. The nucleus is essentially the dense center of an atom where protons and neutrons are packed together.

Electrons are much smaller particles with negative charges that orbit around the nucleus in what's called the "electron cloud." They're incredibly light—only about 1/2000 of an amu. Electrons arrange themselves in rings or shells, with 2 electrons maximum in the first ring and 8 in each outer ring.

Fun Fact: The atomic number of an element (those numbers you see on the periodic table) simply tells you how many protons are in that element's nucleus. There are 118 elements on the periodic table!