Common Chemical Compounds to Know: Formulas, Names, and What They're For
A reference list of the chemical compounds every chemistry student should recognize — hydrocarbons, acids, bases, oxides, salts, and biomolecules — with formulas and what they do.
· 8 min read
Why a Compound List Is Worth Memorizing
Chemistry reuses the same few dozen compounds everywhere. Textbook examples, lab procedures, household products, and real-world reactions all circle back to a small core set of molecules: water, carbon dioxide, methane, ammonia, sodium chloride, ethanol, and so on. Knowing these by sight — name, formula, and what they are used for — makes reading chemistry vastly easier. It is the equivalent of learning vocabulary before you try to read a foreign language.
This article groups the most commonly encountered compounds by class, with their formulas and a one-line description of what they are or where you encounter them.
Hydrocarbons (Alkanes)
Alkanes are saturated hydrocarbons — only carbon-carbon single bonds. They follow the general formula CₙH₂ₙ₊₂. The first few are the most important to recognize.
| Name | Formula | Notable use / role | |---|---|---| | Methane | CH₄ | Main component of natural gas | | Ethane | C₂H₆ | Minor component of natural gas, feedstock for ethylene | | Propane | C₃H₈ | Bottled fuel gas (grills, heating) | | Butane | C₄H₁₀ | Lighter fluid, portable stoves | | Pentane | C₅H₁₂ | Volatile liquid, gasoline component | | Hexane | C₆H₁₄ | Common organic solvent | | Octane | C₈H₁₈ | Reference compound for gasoline rating |
Other Important Organic Compounds
| Name | Formula | Notable use / role | |---|---|---| | Ethylene (ethene) | C₂H₄ | Fruit-ripening hormone, feedstock for polyethylene | | Acetylene (ethyne) | C₂H₂ | Fuel for oxyacetylene welding torches | | Benzene | C₆H₆ | Aromatic solvent, feedstock for many plastics and drugs | | Methanol | CH₃OH | Wood alcohol, solvent, fuel additive | | Ethanol | C₂H₅OH | Drinking alcohol, solvent, biofuel | | Acetic acid | CH₃COOH | The acid in vinegar | | Formaldehyde | CH₂O | Preservative, resin feedstock | | Acetone | (CH₃)₂CO | Nail polish remover, common lab solvent | | Glucose | C₆H₁₂O₆ | Simple sugar, central to metabolism | | Sucrose | C₁₂H₂₂O₁₁ | Table sugar | | Urea | CO(NH₂)₂ | Nitrogen fertilizer, waste product of protein metabolism |
Common Inorganic Oxides
Oxides are compounds of an element with oxygen. These show up constantly.
| Name | Formula | Notable use / role | |---|---|---| | Water | H₂O | The universal solvent | | Hydrogen peroxide | H₂O₂ | Disinfectant, bleaching agent | | Carbon monoxide | CO | Toxic combustion product | | Carbon dioxide | CO₂ | Exhaled gas, greenhouse gas, dry ice (solid form) | | Nitric oxide | NO | Biological signaling molecule, air pollutant | | Nitrogen dioxide | NO₂ | Brown component of smog | | Sulfur dioxide | SO₂ | Volcanic gas, acid rain precursor | | Sulfur trioxide | SO₃ | Intermediate in sulfuric acid manufacture | | Silicon dioxide | SiO₂ | Quartz, main component of sand and glass | | Calcium oxide | CaO | Quicklime, used in cement and steelmaking | | Iron(III) oxide | Fe₂O₃ | Rust | | Aluminum oxide | Al₂O₃ | Corundum, abrasives, aluminum production feedstock |
Common Acids
| Name | Formula | Strong/weak | Notable use / role | |---|---|---|---| | Hydrochloric acid | HCl | Strong | Stomach acid, lab acid | | Sulfuric acid | H₂SO₄ | Strong | Most-produced industrial chemical | | Nitric acid | HNO₃ | Strong | Fertilizer manufacture, explosives | | Phosphoric acid | H₃PO₄ | Weak | Fertilizers, food acidulant (cola) | | Carbonic acid | H₂CO₃ | Weak | Forms when CO₂ dissolves in water | | Acetic acid | CH₃COOH | Weak | Vinegar, acetate feedstock | | Citric acid | C₆H₈O₇ | Weak | Found in citrus fruits | | Hydrofluoric acid | HF | Weak but dangerous | Etches glass |
Common Bases
| Name | Formula | Strong/weak | Notable use / role | |---|---|---|---| | Sodium hydroxide | NaOH | Strong | Lye, drain cleaner, soap-making | | Potassium hydroxide | KOH | Strong | Soft soaps, batteries | | Calcium hydroxide | Ca(OH)₂ | Strong | Slaked lime, used in mortar | | Ammonia | NH₃ | Weak | Fertilizer, household cleaner | | Sodium bicarbonate | NaHCO₃ | Weak | Baking soda, antacid |
Common Salts (Ionic Compounds)
| Name | Formula | Notable use / role | |---|---|---| | Sodium chloride | NaCl | Table salt | | Sodium carbonate | Na₂CO₃ | Washing soda, glass manufacture | | Sodium bicarbonate | NaHCO₃ | Baking soda | | Potassium nitrate | KNO₃ | Saltpeter, gunpowder, fertilizer | | Calcium carbonate | CaCO₃ | Limestone, chalk, seashells | | Calcium phosphate | Ca₃(PO₄)₂ | Main mineral in bones and teeth | | Magnesium sulfate | MgSO₄ | Epsom salt | | Copper(II) sulfate | CuSO₄ | Blue crystals, algaecide, lab reagent | | Silver nitrate | AgNO₃ | Photography, lab reagent | | Ammonium nitrate | NH₄NO₃ | Fertilizer, cold packs | | Ammonium sulfate | (NH₄)₂SO₄ | Fertilizer | | Sodium hypochlorite | NaClO | Household bleach (in solution) |
Gases Worth Recognizing
| Name | Formula | Notable use / role | |---|---|---| | Hydrogen | H₂ | Lightest gas, clean-burning fuel | | Nitrogen | N₂ | 78% of the atmosphere | | Oxygen | O₂ | 21% of the atmosphere, respiration | | Ozone | O₃ | UV-absorbing layer in upper atmosphere | | Chlorine | Cl₂ | Water treatment, bleaching | | Helium | He | Balloons, cryogenics | | Argon | Ar | Inert gas for welding, lightbulb fill | | Neon | Ne | Neon signs |
Household and Industrial Compounds
| Name | Formula | What / where | |---|---|---| | Hydrogen peroxide (3%) | H₂O₂ | Wound disinfectant, bleach | | Sodium hypochlorite | NaClO | Active ingredient in bleach | | Sodium fluoride | NaF | Toothpaste additive | | Potassium iodide | KI | Iodized salt, radiation protection | | Aluminum sulfate | Al₂(SO₄)₃ | Water purification, baking powder | | Magnesium hydroxide | Mg(OH)₂ | Milk of magnesia (antacid) | | Calcium sulfate | CaSO₄ | Gypsum, plaster, drywall |
How to Use This List
Try to memorize name ↔ formula in both directions for the compounds in the first four tables — you will see these most often. For the rest, aim for recognition: when you see CaCO₃ in a problem, "limestone / chalk / seashells" should come to mind immediately, even if you cannot recall the formula from scratch.
A productive drill: cover the name column and try to identify each formula, then cover the formula column and try to write it for each name. Do this a few times a week for two weeks and most of these become reflex.
Connection to the Rest of Chemistry
Every reaction you balance, every stoichiometry problem you solve, and every mechanism you read assumes you know what these compounds are. A balanced equation that says "NaHCO₃ + HCl → NaCl + H₂O + CO₂" tells a story you can read instantly once you recognize baking soda, hydrochloric acid, table salt, water, and carbon dioxide — but it is just a jumble of symbols without that recognition. That is why this list is worth the time.
Practice while it's fresh
Test what you just learned on the interactive periodic table.