Chemistry is a logical science. You can master the essential concepts yourself. You can study these concepts in any order, but it's probably best to start from the top and work your way down, since many concepts build on understanding units, conversion and how atoms and molecules interact.
Introduction to Chemistry: Learn about what chemistry is, what chemists do, and why you would want to study this science.
Units & Measurements: Get a handle on the metric system and the commom units used in chemistry.
The Scientific Method: Scientists, including chemists, are systematic about the way they study the world. Find out how to use the scientific method to collect data and design experiments.
The Elements: Elements are a basic building block of matter. Learn what an element is and get facts for them.
The Periodic Table: The Periodic Table is a way elements can be organized, based on their similar properties. Find out what that table is, how it was designed, and how you can use it to make your study of chemistrymuch easier.
Atoms and Ions: Atoms are single units of an element. Ions can be made up of one or more types of elements and carry an electrical charge. Learn about the parts of an atom and how to identify the different types of ions.
Molecules, Compounds, & Moles: Atoms can be joined together to make molecules and compounds. A mole is a useful way of measuring an amount of atoms or larger components of matter. Define these terms and learn how to perform calculations to express quantities.