High School Chemistry
Chemistry asks what everything around you is made of, and how it changes.
Welcome to the lab. These lessons are written for high school students and anyone curious enough to wonder why salt dissolves or why iron rusts. Each one explains the ideas in plain words, shows how scientists figured them out, and ends with a quiz so you can check yourself.
Start with the periodic table, the map every chemist uses, then move on to bonding to see how atoms join up to make everything from table salt to the water in your glass, to reactions to see how they rearrange into new substances, to stoichiometry to predict how much a reaction makes, to acids and bases to see what pH really measures, and finally to states of matter and the gas laws to see why a balloon shrinks in the cold.
Lessons
The Periodic Table, Explained
How Mendeleev sorted the elements and predicted ones nobody had found yet, how to read groups and periods, and the trends across the table. Explore a clickable table of all 118 elements, then try the Lab Bench Challenge quiz.
Open the periodic table lessonChemical Bonding
Ionic, covalent and metallic bonds, how to draw Lewis structures, and how VSEPR predicts a molecule's shape and polarity. Try the bond-type predictor and the molecule explorer, then take the Bond Builder Challenge.
Open the chemical bonding lessonChemical Reactions and Equations
Signs of a chemical change, conservation of mass, balancing equations, five reaction types, moles and reaction energy. Try the equation balancer and the mole calculator, then take the Reaction Challenge.
Open the chemical reactions lessonThe Mole and Stoichiometry
Avogadro's number, molar mass, the mole map, mole ratios, limiting reactants and percent yield. Try the limiting-reactant simulator and the mole-map calculator, then take the quiz.
Open the stoichiometry lessonAcids and Bases
Brønsted–Lowry acids and bases, strong vs weak, pH and pOH, indicators, neutralization, titration curves and buffers. Try the pH explorer and the titration simulator, then take the Proton Challenge.
Open the acids and bases lessonStates of Matter and the Gas Laws
Solids, liquids and gases, kinetic molecular theory, heating curves and phase diagrams, then Boyle's, Charles's and Avogadro's laws, PV = nRT, STP and Dalton's law. Try the gas particle box and the heating-curve explorer, then take the quiz.
Open the gas laws lessonIntroduction to Organic Chemistry
Carbon's four bonds, alkanes, alkenes and alkynes, structural, condensed and skeletal formulas, functional groups, isomers, polymers and the molecules of life. Try the molecule builder and the functional-group spotter, then take the quiz.
Open the organic chemistry lessonNuclear Chemistry
Isotopes and nuclide symbols, alpha, beta and gamma decay, half-life, fission and fusion, medical isotopes, carbon-14 dating and radiation safety. Try the decay balancer and the half-life simulator, then take the quiz.
Open the nuclear chemistry lessonWhat this course covers, and who it's for
Pull up a stool. This course is written for students in grades 9–12, for self-learners who want to understand chemistry rather than memorize it, and for parents and homeschoolers looking for a clear, free path through the subject.
The units build on each other in order. We start with the periodic table, then see how atoms hold together in chemical bonding, how they rearrange in chemical reactions, how to count them with the mole in stoichiometry, how acids and bases trade protons, and how gases behave in states of matter and the gas laws, meet organic chemistry, the chemistry of carbon, and finish with nuclear chemistry, where the nucleus itself changes.
Every lesson has something to try with your own hands: a clickable periodic table, a bond-type predictor and molecule explorer, an equation balancer, a limiting-reactant simulator, mole calculators, a pH explorer, a titration simulator, a gas particle box, a heating-curve explorer, a molecule builder, a functional-group spotter, a decay balancer and a half-life simulator. Each ends with a quiz you can retake as often as you like.
Each unit also has a "How do we know?" section, because chemistry isn't a list of facts handed down. You'll meet the people and experiments behind the ideas, and see how evidence changed what scientists believed.