A chemical formula shows the elements in a substance and the numbers or ratio of their atoms.
In a molecule, a small number after a symbol counts that element’s atoms. No small number means one atom.
H₂O: 2 hydrogen atoms + 1 oxygen atom.
CO₂: 1 carbon atom + 2 oxygen atoms.
The number in front is the coefficient. It multiplies the whole formula.
2H₂O means 2 water molecules.
Hydrogen: 2 × 2 = 4 atoms.
Oxygen: 2 × 1 = 2 atoms.
Keep the small numbers the same. Changing H₂O to H₂O₂ makes a different substance.
Atoms are rearranged in a reaction. They are not created or destroyed, so each element must have the same number of atoms on both sides.
Count → change coefficients → count again.
Change the big numbers in front, never the small numbers inside a formula.
Read the formula or equation. Tap an answer and build your score.
Small numbers count atoms. Big numbers multiply the formula.
One point for each answer you get right first time.
No timer. Take your time and use a clue whenever you need one.