How do electrons make atoms and chemistry work?

Atoms consist of a nucleus surrounded by electrons, and those electrons determine the atom’s chemical properties. Electrons occupy quantized energy levels, and atoms can gain, lose, or share them to form bonds. Covalent, ionic, and metallic bonding all arise from electromagnetic interactions involving electrons. Because of this, chemistry is basically the physics of electrons in atoms and molecules. The periodic table reflects repeating patterns in electron structure, which is why elements in the same column often behave similarly.