Chemistry
Atoms, bonds, reactions and solutions. 110 topics, from beginner to advanced.
Browse all 110 Chemistry topics →Featured
Visual showcases to start withThe Bohr Model of the Atom
Electrons orbit the nucleus in discrete shells. Change the proton count to build any element.
Ionic Bonding
When the electronegativity gap is large, one atom takes an electron and opposite charges attract.
Covalent Bonding
Atoms share electron pairs. Equal sharing between identical atoms gives a nonpolar bond.
Collision Theory
Reactions happen only when particles collide with enough energy and the right orientation.
Catalysts
A catalyst offers an easier path with a lower activation energy and is not used up.
Le Chatelier’s Principle
Disturb an equilibrium and it shifts to partly undo the change. Change the rate constants to see it.
Acid–Base Titration
Add base drop by drop: the pH leaps near the equivalence point where acid and base cancel.
Galvanic Cells and Batteries
A spontaneous redox reaction pushes electrons through an external circuit.
Electrolysis
Electric current drives non-spontaneous reactions, splitting compounds into elements.
Chromatography
Components of a mixture travel at different speeds through a stationary phase.
Distillation
Separate liquids by their different boiling points.
Lithium-Ion Batteries
Lithium ions shuttle between electrodes as the cell charges and discharges.
Popular
Classic topics most learners start withThe Periodic Table
Elements arranged by atomic number: columns share chemical behaviour.
States of Matter
Adding energy moves particles from a rigid solid to a flowing liquid to a free gas.
The pH Scale
A logarithmic scale of hydrogen-ion concentration: each unit is a tenfold change.
Water and Hydrogen Bonding
Water’s polarity creates hydrogen bonds, giving high boiling point, surface tension and ice that floats.
Chemical Equilibrium
Forward and reverse reactions reach equal rates and concentrations stop changing.
Exothermic Reactions
Products sit lower in energy than reactants, so heat is released to the surroundings.
Combustion
A fuel reacts with oxygen to release heat, carbon dioxide and water.
Radiocarbon Dating
Carbon-14 decays with a 5730-year half-life, letting us date ancient organic remains.
Fermentation
Yeast converts sugar into ethanol and carbon dioxide without oxygen.
Acid Rain Formation
Sulfur and nitrogen oxides dissolve in cloud water to form acids that damage ecosystems.
The Ozone Layer
Stratospheric ozone absorbs harmful UV; CFCs destroy it in a catalytic cycle.
The Haber Process
Nitrogen and hydrogen combine under pressure and heat to make ammonia fertiliser.
All 110 Chemistry topics
🌱 Beginner
- The Bohr Model of the Atom
- Hydrogen, the Simplest Atom
- Carbon and Its Four Bonds
- Noble Gases and Full Shells
- Sodium: Giving Away an Electron
- Transition Metals
- The Periodic Table
- Groups and Periods
- Alkali Metals
- The Halogens
- Metalloids
- Electronegativity Across a Period
- Atomic Radius Trend
- Ionisation Energy Trend
- Alkali Metal Melting Points
- Boiling Points of the Noble Gases
- Densities of Common Metals
- Ionic Bonding
- Covalent Bonding
- Polar Covalent Bonds
- Bond Energies
- States of Matter
- Helium: A Full First Shell
- Oxygen and Its Six Valence Electrons
- Uranium on the Periodic Table
- Noble Gases Column
- Electronegativity of Group 1
- Halogen Electronegativity
- Atomic Radius Down a Group
- First Ionisation Energy of Group 1
- Melting Points of Period 3
- Molar Masses of Common Gases
- Typical pH Values
- Heats of Combustion of Fuels
- Collision Theory at Low Temperature
- Collision Theory with a Low Barrier
- Highly Exothermic Reaction
- Weak Acid pH
- Seawater is Slightly Basic
- Titration of a Dilute Acid
- Titration of a Concentrated Acid
🔧 Intermediate
- Water and Hydrogen Bonding
- Metallic Bonding
- Collision Theory
- Activation Energy
- Catalysts
- Exothermic Reactions
- Endothermic Reactions
- Temperature and Reaction Rate
- Le Chatelier’s Principle
- The pH Scale
- Strong Acids
- Bases and Alkalinity
- Acid–Base Titration
- Henderson–Hasselbalch Buffer
- Arrhenius Equation
- Beer–Lambert Law
- Dilution
- Raoult’s Law and Boiling Point Elevation
- Radiocarbon Dating
- Galvanic Cells and Batteries
- Equilibrium Favouring Products
- Equilibrium Favouring Reactants
- Nonpolar Bond in Oxygen
- Hydrogen Fluoride: Very Polar
- Carbon–Hydrogen: Almost Nonpolar
- Ideal Gas Molar Volume
- Van der Waals Gas
- Reaction Order Plots
- Rate Law Dependence on Concentration
- Half-Life of First-Order Reactions
- Solubility vs Temperature
- Freezing Point Depression
- Osmotic Pressure of a Solution
- Buffer Capacity
- Standard Cell Potentials
- Faraday’s Law of Electrolysis
- Balancing Chemical Equations
- Stoichiometry Road Map
- How Soap Cleans
- Fractional Distillation of Crude Oil
- Hydrogen Fuel Cells
🚀 Advanced
- Chemical Equilibrium
- Nernst Equation
- Radioactive Isotopes
- Combustion
- Electrolysis
- Corrosion and Rusting
- The Haber Process
- Distillation
- Chromatography
- Polymerisation
- Fermentation
- The Ozone Layer
- Acid Rain Formation
- Entropy and Spontaneity
- Gibbs Energy and Equilibrium Constant
- Oxidation and Reduction (Redox)
- Limiting Reagent
- Catalytic Converters
- Lithium-Ion Batteries
- Making Ammonia to Feed the World
- The Contact Process
- Water Treatment
- Green Chemistry Principles
- Isomers: Same Atoms, Different Molecules
- Functional Groups in Organic Chemistry
- Esterification
- Addition Polymerisation of PVC
- Biodegradable Plastics
Frequently asked questions
What will I learn in Chemistry?
Atoms, bonds, reactions and solutions. Each topic has a live animation, a lesson and a quick quiz.
Where should I start?
Try “The Periodic Table” from the Popular list, or any beginner topic in Browse.
Are the topics in a set order?
Browse groups topics by level, with beginner topics first. Each topic’s FAQ names the topic to read before it.
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