Science · Grades 8–11
Chemical equations: atom bookkeeping · revision card
Change coefficients in front of formulas, not the subscripts that identify a substance.
Keep these ideas clear
Balance coefficients
Change coefficients in front of formulas, not the subscripts that identify a substance.
Count each element
Count atoms on each side separately before deciding whether an equation is balanced.
Two useful examples
How many hydrogen atoms are represented by 3H₂O?
3 × 2 = 6
6
How many oxygen atoms are represented by 3H₂O?
3 × 1 = 3
3
Explain it without looking
- Why does balancing an equation not by itself tell you how fast a reaction occurs?
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Learning preview · teacher review required. Grade bands are approximate, not official curriculum alignment.