All matter is composed of very small particles called atoms.All atoms of a given element are identical.Atoms cannot be created, destroyed, or subdivided.In chemical reactions, atoms combine with or separate from other atoms.In chemical reactions, atoms combine with each other in simple, whole-number ratios to form combined atoms
Atoms consist of three basic particles: protons, electrons, and neutrons. The nucleus (center) of the atom contains the protons (positively charged) and the neutrons (no charge). The outermost regions of the atom are called electron shells and contain the electrons (negatively charged).