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Read a formulaTap a number or a symbol to see what it counts
  • H₂O: Water
  • O₂: Oxygen
  • CO₂: Carbon dioxide
  • NaCl: Sodium chloride (common salt)
  • H₂SO₄: Sulphuric acid
  • Ca(OH)₂: Calcium hydroxide
  • 2 H₂O: Water
  • 2 CO₂: Carbon dioxide
  • 2 H₂SO₄: Sulphuric acid

Tap a number or a symbol in the formula. No big number in front means one molecule.

Atoms counted

Each box is one molecule. Circles are atoms, coloured by element.

Try changing a number

Big numberin front: how many copies
Small number after the bracketin the formula: which substance it is
Formulae from the unit:

For a small number, press Shift and _ (or the x₂ button), then type the number: H₂O. A number at the front is a big number: 2 H₂O. Capitals and lowercase matter: CO is carbon and oxygen, Co is cobalt.

The formulae come from the unit booklet (page 12) and the notes for 1.2.