Balancing equations
I can balance chemical equations, and explain why it is important to ensure symbol equations are balanced.
Balancing equations
I can balance chemical equations, and explain why it is important to ensure symbol equations are balanced.
Lesson details
Key learning points
- All the atoms in the reactants of a chemical reaction are reorganised to form all the products of the reaction.
- There must be an equal number of each type of atom on both the reactant and product side of the equation.
- Chemical formulae cannot be altered to balance a reaction equation; only coefficients can change.
- Atoms cannot be created or destroyed. During a chemical reaction, atoms are simply rearranged into products.
Common misconception
Pupils sometimes think that chemical formulae can be changed to balance atoms.
Put boxes around each formula in the equation / pretend there is a bucket of pre-made molecules which they can use to balance the number of atoms on each side. Stress that it takes perseverance and practice before equations are balanced.
Keywords
Word equation - A word equation is a way of describing a reaction using the chemical names of the reactants and products.
Chemical formula - A chemical formula represents a substance using element symbols and the number / ratio of atoms of each element in the substance.
Symbol equation - A symbol equation is a way of describing a reaction using the chemical formulae of the reactants and products.
Balanced symbol equation - A balanced symbol equation describes a reaction using a symbol equation with coefficients, which ensure there are equal numbers of atoms of each element on both sides of the symbol equation.
Coefficient - A coefficient is the number placed in front of a chemical formula to balance an equation; it multiplies all the atoms in the formula and shows the ratio of substances in a reaction.
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
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Starter quiz
6 Questions
MgO
AlI₃
CuCO₃
NaOH
K₂SO₄
SrCl₂
H₂O (l)
H₂O (s)
H₂O (g)
NaCl (aq)
Hg (l)
He (g)
Exit quiz
6 Questions
describes a chemical reaction using chemical names
represents a substance using element symbols and numbers
describes chemical reactions using chemical formulae and state symbols