Chemtutor

From site:  Chemistry help is available here for high school or college students. Chemtutor begins with the fundamentals and gives expert help with the most difficult phases of understanding your first course in chemistry. Chemtutor is not necessarily a complete text for your course or a complete outline, but we are proud to offer some insightful help in the parts of primary chemistry that have been, from our experience, the hardest for students to grasp. Chemtutor can be a part of a course of study for independent students, a resource for chemistry teachers, a review, or a tutoring program for students taking high school or basic college chemistry.