Atom
Definition 1 of 3
Pro Tip 1/3
Chemical Composition
Atoms bond together to form molecules, which make up matter. Water is composed of hydrogen and oxygen atoms.
Pro Tip 2/3
Indivisible Concept
Historically, atoms were thought to be indivisible; now we know they consist of smaller particles. Atoms are made up of protons, neutrons, and electrons.
Pro Tip 3/3
Unique Identity
Every element on the periodic table is defined by the number of protons in its atoms. Carbon atoms have six protons each.