If you are a student starting a chemistry course this semester. Then you may want to review the following concepts before you start you chemistry course.
I have selected some videos for you.
Make sure you watch all these videos and practice all the questions you may have associated with the lessons.
How to read the periodic table data
Atomic Mass Unit
Moles
Naming of Simple Ionic Compounds
Naming Simple Molecular or Covalent Compound
Types of Reactions