Reactants → Products
A chemical story in one short line.
A story in a line
A magnesium ribbon burns with a dazzling white flame and turns into a white powder. This sentence is long. Chemists squeeze it into one short line.
What would you put on the left of the arrow and what on the right?
What this lesson covers
The idea
A word-equation writes the reactants (substances that undergo chemical change) on the LHS and the products (new substances formed) on the RHS, joined by plus signs, with an arrow pointing to the products to show the direction of reaction.
A story in a line
A magnesium ribbon burns with a dazzling white flame and turns into a white powder. This sentence is long. Chemists squeeze it into one short line.
What would you put on the left of the arrow and what on the right?
- Left: what we start with. Right: what we get.
- Left: what we get. Right: what we start with.
- It does not matter
Build the line
Tap a tile, then tap the box where it belongs.
Left, plus, arrow, right
A word-equation writes the reactants on the LHS and the products on the RHS, joined by plus signs. The arrow points to the products and shows the direction of the reaction.
LHS = left-hand side. RHS = right-hand side.
- Name | Meaning | Example
- Reactants | Substances that undergo chemical change | Magnesium, Oxygen
- Products | New substances formed | Magnesium oxide
Notes
A word-equation writes the reactants (substances that undergo chemical change) on the LHS and the products (new substances formed) on the RHS, joined by plus signs, with an arrow pointing to the products to show the direction of reaction.
Check yourself
In Magnesium + Oxygen → Magnesium oxide, which is the product?
What does the arrowhead show?
Iron nails dipped in copper sulphate solution make iron sulphate and copper. Which word-equation is right?
- Magnesium. Magnesium is on the LHS. It undergoes the change, so it is a reactant.
- Oxygen. Oxygen is on the LHS too. It is a reactant.
- Magnesium oxide — correct. Yes! It is the new substance formed, on the RHS.
- The reaction goes from reactants towards products — correct. Yes! The arrowhead points at the products.
- That the two sides are equal in colour. The arrow says nothing about colour. It shows direction.
- That the product is heavier. The arrow shows direction, not weight.
- Iron sulphate + Copper → Iron + Copper sulphate. The reactants and products are swapped. The nails and copper sulphate are what we start with.
- Iron + Copper sulphate → Iron sulphate + Copper — correct. Yes! Reactants on the left, products on the right.
- Iron + Copper sulphate = Iron sulphate + Copper. Use an arrow, not an equals sign: it shows the direction of the reaction.