Parts of a Chemical Equation

One balanced equation, 2H₂ + O₂ → 2H₂O, piece by piece: 8 parts.

Parts of a Chemical Equation

Name Date

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1 2 3 4 5 6 7 8
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Write the name of each numbered part.Answer key

  1. Coefficient
  2. Element symbol
  3. Subscript
  4. State symbol
  5. Plus sign
  6. Yields arrow
  7. Reactants
  8. Products

Drawn for this site by script, 2026-09-26. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

Next step Next: inside the atoms: the atom diagram

All 8 parts on the diagram

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All 8 parts 8

  1. Coefficient The number in front of a formula. It tells how many molecules of it take part. If none is written, it is 1.
  2. Element symbol The letter or letters standing for an element. H is for hydrogen, O for oxygen.
  3. Subscript The small number after an element symbol. It gives how many atoms of that element are in one molecule.
  4. State symbol The letter in brackets showing a substance's state. (s) solid, (l) liquid, (g) gas, (aq) dissolved in water.
  5. Plus sign Separates two substances on one side of the equation.
  6. Yields arrow Points from the reactants to the products. It shows the direction of the reaction. It is read yields.
  7. Reactants The starting substances, written on the left-hand side.
  8. Products The substances formed in the reaction, written on the right-hand side.

How this list was compiled: Read 2026-09-26. Wikipedia, Chemical equation, https://en.wikipedia.org/wiki/Chemical_equation : reactants (starting substances) on the left and products (substances formed) on the right, with a plus sign between substances on the same side and an arrow pointing toward the products showing the direction; each substance written as its chemical formula, an optional stoichiometric coefficient in front giving how many entities take part, 1 if not written; the arrow read as yields; state symbols in parentheses: (s) solid, (l) liquid, (g) gas, (aq) aqueous solution. Wikipedia, Chemical formula, https://en.wikipedia.org/wiki/Chemical_formula : element symbols for the atoms of each element, with subscripted whole numbers for how many. The worked equation is balanced: 4 hydrogen and 2 oxygen atoms on each side. Licence: own work

The drawing: Drawn for this site by script, 2026-09-26. Own work. Licence: own work

How it works

The parts of a chemical equation on one balanced example, hydrogen and oxygen making water: the reactants and products either side of the arrow, and every number, letter and sign in between.

Read the full guide

The two sides

Reactants, the starting substances, go on the left. Products, the substances formed, go on the right. The yields arrow points from one to the other, and a plus sign separates two substances on the same side.

The numbers and letters

Each formula is element symbols with subscripts: H₂O has two hydrogen atoms and one oxygen. A coefficient in front says how many molecules take part. A state symbol in brackets says solid, liquid, gas or aqueous.

  • Coefficients count molecules, subscripts count atoms inside one molecule: change a subscript and you have a different substance.

Questions and answers

What is the difference between a coefficient and a subscript?

A coefficient is the big number in front of a formula and says how many molecules take part. A subscript is the small number after an element symbol and says how many of that atom are in one molecule.

What does the arrow in a chemical equation mean?

It points from the reactants to the products and shows the direction of the reaction. It is read as yields.

What do (s), (l), (g) and (aq) mean?

They are state symbols: solid, liquid, gas and aqueous, meaning dissolved in water.

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