This document provides an overview of atoms and elements. It defines atoms as the building blocks of matter and notes they contain protons, neutrons, and electrons. Elements are made of the same type of atom and are the basic substances that can be combined to form all chemical compounds and molecules. The periodic table lists all known elements and provides each element's atomic number, symbol, name, and atomic mass. The document also describes two common atomic models - the Bohr model, which depicts the subatomic particles within an atom, and the Lewis dot structure, which represents only the outer shell electrons through dots or lines.