What's the difference between a physical change and a chemical change? What are elements, compounds, pure substances, and mixtures? So many definitions to learn! Don't worry, Professor Dave will take you through the details. Watch the whole General Chemistry playlist: Study for the AP Chemistry exam with me: Organic Chemistry Tutorials: Biochemistry Tutorials: Biology Tutorials: Classical Physics Tutorials: Modern Physics Tutorials: Mathematics Tutorials: EMAIL► ProfessorDaveExplains@ PATREON► Check out "Is This Wi-Fi Organic?", my book on disarming pseudoscience! Amazon: Bookshop: Barnes and Noble: Book Depository: