1. Introduction: When Words Are Not Enough
Watch a piece of magnesium ribbon burn. It flares up with a blinding white light and leaves behind a white powder. In words, you would say: "magnesium burns in air to form magnesium oxide."
That sentence is fine for talking. But a chemist needs to say three more things that words hide:
- Exactly which substances react, and exactly what forms.
- How much of each — the counting.
- The conditions, like heat or a catalyst.
A chemical equation is a shorthand that packs all of this into one line. Instead of a paragraph, you write:
2Mg + O₂ → 2MgO
By the end of this lesson you will be able to turn a sentence like "magnesium burns in air" into a correct, balanced equation — and read one back into plain words.
Stop scrolling. Try it in your head before reading on: in "magnesium burns in air," what is actually reacting with the magnesium? (Hint: what is "air" made of that things burn in?)