Today is rung 3 of 5 on this topic
Bonding, reactions and balancing equations
Can do: Predicts bond types, writes and balances equations, and explains balancing by conservation of atoms.
Why it matters
Balancing is trivial once conservation of atoms is understood, and impossible to remember as a procedure without it.
What it looks like when it's wobbly
Balances by trial and error, or illegally changes subscripts to make the numbers work.
⏱️ Two-minute check
"Balance the combustion of methane. Why can't you just change the subscripts?"
Solid looks like: CH₄ + 2O₂ → CO₂ + 2H₂O, and knows subscripts define the substance itself.
The full activity for this topic · 30 minutes
Count the Atoms
- 1Model a reaction with beads: the same beads must appear on both sides, rearranged.
- 2Balance by counting each element in a table, one row per element.
- 3Show what happens if a subscript is changed — it becomes a different substance entirely.
- 4Balance five equations of increasing difficulty using the table method.
- 5Do a real one: vinegar and baking soda, weighed sealed to confirm conservation.
If it's too hard
Two-element equations with a counting table.
If it's too easy
Combustion of larger hydrocarbons, and ionic equations.
Say this
"Changing the subscript makes it a different chemical. You can only change how many molecules there are."