Chemistry · KS3 Y8 · Chemical Reactions

Chemical reactions & equations

Chemical reactions & equationsFree12:12Heddy Score 3 of 7, below the standard
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What you need to know

  • A word equation names the reactants and products; a symbol equation replaces each name with its formula.
  • A balanced equation has the same number of each type of atom on both sides of the arrow, because atoms are only rearranged.
  • You balance an equation by putting numbers in front of formulae, never by changing the small subscript numbers.
  • Changing a subscript changes the substance itself, e.g. H2O (water) would become H2O2 (hydrogen peroxide).
  • A simple tally chart of atoms on each side helps you balance equations such as N2 + 3H2 → 2NH3.

In this clip

Runs 12:12, from 0:00 to 12:12 of the full video.

Heddy Score3/7, Below the standard
See the seven stars
  • Trusted source · passed. The creator's own upload, live and playable here.
  • On the map · not judged yet. A teacher watched it: it mainly teaches this map topic.
  • Spec-true · not judged yet. Accurate, and right for the current UK specification.
  • Focused · passed. One idea, short enough to watch in one go.
  • Accessible · passed. Good captions, clear sound and pictures.
  • Safe for children · not judged yet. Right for 11 to 16 year olds, with no sales pitch.
  • Proven · not judged yet. Earned from our students: they learn from it, find it helpful and watch it to the end.
★ passed · ☆ pending · ✕ failed
Our students

Not enough students yet

Our own students' answers. These are what move ★7 Proven.
On YouTube

2.71M views · 30.4K likes · Tyler DeWitt 1.61M subscribers

As reported by YouTube on 2026-11-02. Not part of the Heddy Score.
How the Heddy Score works

Why we picked it

Uses atom diagrams to show why equations must balance, then builds a step-by-step method that students can copy.

Tyler DeWitt on YouTubechecked 2026-10-22

Plays from youtube-nocookie.com. No YouTube cookies until you press play.