Audience: Students; Grades: 4-5; Subject: Science. (2005) Explains how chemical elements are classified by introducing the periodic table. Examines the similarities between the chemical properties and the regular trends in the physical properties within each periodic group. Introduces the history of periodic law, defines atomic structure, atomic number, atomic mass, and identifies groups of chemical elements. Illustrates the atomic structures of some simple elements and their relationship to the periodic table. Program concludes with a ten-question video quiz.