How to balance chemical equations for the TEAS 7, with worked examples
Written and reviewed by Brittany Scott, BSN, RN, CCM · 4 min read · Updated November 2026
Short answer
To balance a chemical equation on the TEAS, change only the coefficients in front of each formula until every element has the same number of atoms on both sides, and never change the subscripts. Balancing sits under ATI's TEAS 7 chemistry objective "Describe chemical reactions," one of six chemistry objectives sharing 8 scored questions.
Is balancing equations on TEAS 7?
ATI's TEAS 7 content outline lists six chemistry objectives, including S.3.3, "Describe chemical reactions," and S.3.4, "Demonstrate how conditions affect chemical reactions." Chemistry has 8 scored questions in total. ATI does not publish an item list that names balancing by itself, so treat it as one skill inside the reactions objective, not a guaranteed question.
It is still worth the time, because a balanced equation is how chemistry describes any reaction. If you can balance one, you can also read reactants and products, spot the reaction type, and check that an answer choice is even possible.
The two rules that never change
Rule one comes from the law of conservation of matter: each element must have the same number of atoms on the reactant side and the product side. Rule two: change only coefficients, the numbers written in front of a formula. A coefficient of 1 is left unwritten, and the final answer uses the smallest whole numbers.
Subscripts are off limits because, as OpenStax puts it, they define the identity of the substance. Changing H2O to H2O2 does not balance water; it turns water into hydrogen peroxide. Any answer choice that changed a subscript is wrong even if the atom counts happen to match.
Three worked examples
Water splitting: H2O gives H2 + O2. Oxygen is 1 on the left and 2 on the right, so put a 2 in front of H2O. Now hydrogen is 4 on the left and 2 on the right, so put a 2 in front of H2. Result: 2H2O gives 2H2 + O2, with 4 hydrogen and 2 oxygen on each side.
Methane burning: CH4 + O2 gives CO2 + H2O. Carbon is already 1 and 1. Hydrogen is 4 on the left, so write 2H2O. Oxygen on the right is now 2 + 2 = 4, so write 2O2. Result: CH4 + 2O2 gives CO2 + 2H2O. Ammonia: N2 + H2 gives NH3 balances as N2 + 3H2 gives 2NH3, with 2 nitrogen and 6 hydrogen per side.
A fast check for multiple-choice items
On a multiple-choice question you do not have to balance from scratch. For each option, multiply every coefficient by the subscript of each element in that formula and add up each element on both sides. OpenStax gives this same tally as the way to verify a balanced equation. The first option where every element matches is your answer.
Order the work to save time: first cross out any option with altered subscripts, then check the element that appears in the fewest formulas, and leave oxygen for last in combustion reactions, since it shows up in several products. Most wrong options fail on the first element you count.
Reaction types to recognize
OpenStax Chemistry groups reactions into precipitation reactions, where dissolved substances form a solid; acid-base reactions, where an acid and a base form a salt and water; and oxidation-reduction reactions, where electrons move, with oxidation as loss of electrons and reduction as gain. Combustion, a fuel reacting with an oxidant to release heat and light, is a kind of redox reaction.
Many study lists also use the shape-based names synthesis (two substances combine, like ammonia above) and decomposition (one substance breaks apart, like water splitting). ATI's outline does not say which naming system its items use, so be able to recognize a reaction by either label.
Sources
ATI TEAS Version 7 Content Outline (PDF). Chemistry objectives S.3.1 to S.3.6 including S.3.3 and S.3.4 wording; 8 scored chemistry questions (checked November 2026).
OpenStax Chemistry 2e, 4.1 Writing and Balancing Chemical Equations. Conservation of matter; change coefficients not subscripts; subscripts define identity; coefficient of 1 omitted; smallest whole numbers; tally check; water decomposition example.
OpenStax Chemistry 2e, 4.2 Classifying Chemical Reactions. Precipitation, acid-base and redox classes; neutralization gives salt and water; oxidation as electron loss and reduction as gain; combustion as a redox subclass.
Common questions
How do you balance an equation fast?
Balance the element that appears in the fewest formulas first, leave oxygen and hydrogen for last, change only coefficients, then tally each element on both sides. On multiple choice, test the options instead of starting from scratch.
What reaction types are on the TEAS?
ATI's TEAS 7 outline says only "Describe chemical reactions" and does not list types. Know precipitation, acid-base (neutralization), oxidation-reduction and combustion, plus synthesis and decomposition by their shapes.
Is balancing equations on TEAS 7?
It falls under the chemistry objective on describing chemical reactions, one of six chemistry objectives sharing 8 scored questions. ATI does not name balancing as its own item type, so expect it as one possible question, not several.