The World book Encyclopedia . The diameter of an atom ranges from about 0.1 to 0.5 nanometer. According to Rutherford, the radius of the entire atom was 0.00000001 cm. Baylis, William E. Macmillan Encyclopedia of Physics. An atom is one of the basic units of matter.
Atoms form the building blocks of the simplest substances, the chemical elements.
Nearly everything on earth is made up of atoms. Each element consists of one basic kind of atom. Tiny as atoms are, they consist of even more minute particles. The three basic types are protons, neutrons, and electrons. Protons have a positive electrical charge, and electrons have a negative charge.