Chemical formulas of common compounds: the list of 100 (compounds and the common element molecules) with the chemical name, the formula, the molar mass and the everyday name (acetone CH₃COCH₃, acetic acid CH₃COOH, lithium hydroxide LiOH, perchloric acid HClO₄, sodium benzoate, butanoic acid, baking soda, bleach, vinegar, rust, chalk, Epsom salt, dry ice, laughing gas), grouped as gases, organic compounds, acids, bases, salts and oxides, with how to read a formula and a printable chart

"Acetone formula", "ethanoic acid formula", "LiOH", "HClO4": students look up one compound at a time, in a hurry, usually to finish a worksheet or check a name against a formula. This page is the list those lookups add up to: a hundred compounds and element molecules that school and first-year chemistry use, each with its systematic name, its formula, its molar mass (so the mole calculations can start at once) and the name it goes by in the kitchen, the garage or the news, grouped so that the acids are together, the salts are together and the pattern shows. Before the chart, two short sections on how to read a formula and how to find a molar mass. The printable has the whole chart on two pages.

Download the chemical formulas chart (PDF) (the 100 formulas in six groups with name, formula, molar mass and everyday name, the rules for reading a formula, the molar-mass method and the atomic masses used; two pages, free).

How to read a formula

• A capital letter, with a lowercase letter if there is one, is one element: C is carbon, Cl is chlorine, Co is cobalt, CO is carbon and oxygen.
• A subscript after a symbol counts that element's atoms in the molecule or formula unit: H₂O has two hydrogens and one oxygen (no subscript means one).
• A subscript after a bracket multiplies everything inside: Ca(OH)₂ is one calcium, two oxygens, two hydrogens; (NH₄)₂SO₄ is two nitrogens, eight hydrogens, one sulfur, four oxygens.
• A dot joins water of crystallisation: CuSO₄·5H₂O is copper sulfate with five waters per formula unit.
• A coefficient in front counts whole molecules: 3 H₂O is three molecules, six hydrogens and three oxygens altogether.
• Organic formulas are often written to show the structure: CH₃COOH shows the methyl group and the carboxyl group; the molecular formula C₂H₄O₂ counts the same atoms without the structure.

Molar mass is the sum of the atomic masses of all the atoms, in grams per mole. Water: 2 × 1.008 + 16.00 = 18.02 g/mol. Acetone, C₃H₆O: 3 × 12.01 + 6 × 1.008 + 16.00 = 58.08. The atomic masses used below: H 1.008, C 12.01, N 14.01, O 16.00, Na 22.99, Mg 24.31, Al 26.98, Si 28.09, P 30.97, S 32.06, Cl 35.45, K 39.10, Ca 40.08, Ti 47.87, Fe 55.85, Cu 63.55, Zn 65.38, Br 79.90, Ag 107.87, I 126.90, Li 6.94, Mn 54.94, Ba 137.33.

Gases and small molecules

Organic compounds

Acids

The strong acids and bases page has what strong means and the pKa values.

Bases

Salts

Oxides and minerals

Finding a molar mass: three worked examples

• Perchloric acid, HClO₄: 1.008 + 35.45 + 4 × 16.00 = 100.46 g/mol.
• Epsom salt, MgSO₄·7H₂O: 24.31 + 32.06 + 64.00 + 7 × 18.02 = 246.47 g/mol.
• Sodium benzoate, C₆H₅COONa, which is C₇H₅O₂Na: 7 × 12.01 + 5 × 1.008 + 2 × 16.00 + 22.99 = 144.10 g/mol.

From the molar mass, moles = mass ÷ molar mass: 29 g of acetone is 29 ÷ 58.08 = 0.50 mol.

Where it sits in school

Reading and writing formulas is grade 8 to 10 (US physical science and chemistry), GCSE Chemistry, Year 9 and 10 Science in Australia and CBSE Class 9 (Atoms and Molecules) and 10; molar mass and moles from grade 10 and 11 and Class 9 onwards; the organic names (propanone, ethanoic acid) from GCSE, Class 10 (Carbon and its Compounds) and grade 11. The errors are the ones the chart prevents: CO for cobalt, a bracket's subscript applied to one atom only, and the water of crystallisation left out of a molar mass.

Download the chemical formulas chart (PDF)

Where to get help

A 1-on-1 online chemistry class with a tutor who holds a master's degree in chemistry, for grades 8 to 12, GCSE and A level, the Australian years and CBSE Class 9 to 12: formulas built from ions and valencies on the shared screen, molar masses worked line by line, then the mole calculations and the naming rules for organic compounds. The recording and notes after every class, the same tutor every week, US$10 to $13 an hour. The chemistry page has the courses; the free 30-minute first class is a real lesson, usually on the homework the student brings.

Questions parents ask

See how we teach this, 1-on-1 online →