Learn about energy levels, sub levels, and orbitals in this video. This is a foundation to understanding how to write electron configurations (discussed in video 028 Electron Configurations).
This is a review of chapters 3 & 4. The topics covered include physical and chemical changes, physical and chemical properties, mixtures, separation of mixtures, pure substances, elements, compounds, isotopes and Rutherford model of the atom.
It is recommended that you work the review sheet first then check your answers and then scroll to the question number that you need help with in the video. You have to practice in chemistry, working the review sheet first will help you to identify what concepts you need to focus on the most while studying.