Scholastic
Scholastic: Study Jams! Science: Matter: Elements & Compounds
A video and a short quiz on elements, how they combine through chemical reactions to make compounds, and how to write the chemical formulas for water and salt.
CK-12 Foundation
Ck 12: Percent Composition and Empirical & Molecular Formulas
[Free Registration/Login may be required to access all resource tools.] In this online tutorial students will learn to calculate the percent composition of a compound either from mass data or from the chemical formula. They will use...
Purdue University
Purdue University: Elements, Compounds & Mixtures
Provides definitions and characteristics of elements, compounds, and mixtures, and gives an animated image of each.