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Atomic Model Chemical Formula Year 10 Word and Symbol Equations A chemical equation shows the reactants and products in a chemical reaction, and the proportions in which they react. The names of the reactants and products can be written in a word equation. The formulae for the reactants and products can also be written in a symbol equation. Numbers may also appear in front of the formulae in symbol equations. These show the proportions in which the reactants combine to form the products. For example, consider the following word and symbol equations for a neutralisation reaction Zinc Oxide + Hydrochloric Acid -> Zinc Chloride + Water ZnO + 2HCl -> ZnCl2 + H2 O Example: Burning Magnesium Magnesium + Oxygen -> Magnesium Oxide 2Mg solid + O2 gas -> 2MgO solid in powder form R Laugesen 16/07/2008 Atomic Model Chemical Formula Year 10 Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Name the elements we started with: Name the elements we ended with: Did the elements stay separate? Was a new product formed? If yes, what was the new product? Were any new elements added? Endothermic or exothermic? What kinds of energy? Were any elements lost? _____________________ _____________________ _____________________ _____________________ _____________________ _____________________ _____________________ _____________________ _____________________ Was it a physical or chemical change? _____________________ Tearing Paper 1. 2. 3. 4. 5. Is tearing paper a physical or chemical change? ______________ Does the paper look different after being torn? ______________ Is the paper still paper? ______________ The chemical properties of the paper ___________ changed A chemical equation ____________ be written to show a physical change. R Laugesen 16/07/2008