Atoms, molecules, and ions
Chemical reactions and stoichiometry
Electronic structure of atoms
Gases and kinetic molecular theory
States of matter and intermolecular forces
Acids and bases
Acid-base equilibria and solubility equilibria
Redox reactions and electrochemistry
Give a great answer
Be a guide
We're teaching each other – so don't just answer "Yes" or "No", share your answer the way your favorite teacher would.
Vote, don't echo
If someone has already answered the question well, don't repeat their answer – vote it up instead.
Flag inappropriate posts
Here are posts to avoid making. If you do encounter them, flag them for attention from our Guardians.
- disrespectful or offensive
- an advertisement
- low quality
- not about the video topic
- soliciting votes or seeking badges
- a homework question
- a duplicate answer
- repeatedly making the same post
- a tip or thanks in Questions
- an answer that should be its own question
about the site
- a question about Khan Academy
- a post about badges
- a technical problem with the site
- a request for features
Visit a video or article to ask a question.