1. L3: Chemical Formulas and Word Equations Learning Objectives: 1.Understand what information a chemical formula tells you. 2.Write simple word equations.

2. Chemical Formulae Chemical formula: tells you how many atoms of each element is in a molecule. Example: Water H 2 O H H O hydrogen 2 atoms of hydrogen oxygen 1 atom of oxygen

3. Word Equations Word equations are used to represent chemical reactions. Reactants = starting materials, written on the left side of the arrow Products = substances formed in the chemical reaction, written on the right side of the arrow Reactants  Products

4. Example A chemical reaction happens when magnesium is added to hydrochloric acid. Hydrogen gas is given off in this reaction. Magnesium chloride is also formed. Word Equation Magnesium + Hydrochloric Acid  Hydrogen + Magnesium Chloride