C1.3 Chemical reactions

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Across
  1. 1. A change that is reversible, in which new substances are not made. Examples of physical changes include changes of state, and dissolving.
  2. 3. a material that releases energy when it burns
  3. 6. a change in which energy is absorbed from the surroundings
  4. 7. Possible source of danger
  5. 8. A change in which atoms are rearranged to create new substances.
  6. 9. an equation in which the reactants and products in a chemical reaction are represented by words (their names). The arrow in the equation means 'reacts to make'
  7. 10. A chemical change in which a substance combines with oxygen, for example; when iron oxidises, forming rust
  8. 11. A chemical reaction that breaks down compounds into simpler products.
  9. 12. A rapid reaction between oxygen and fuel that results in heat and light
  10. 13. a change in which energy is released to the surroundings
  11. 14. The chance of damage or injury from a hazard
Down
  1. 1. a substance that forms in a chemical reaction
  2. 2. the principle stating that matter is not created or destroyed during a chemical reaction. The total mass of products produced is equal to the total mass of reactants used.
  3. 3. A fuel made from the remains of animals and plants that died millions of years ago. Fossil fuels include coal, oil, and natural gas.
  4. 4. Resources that cannot be replenished at rate they are used. The will one day run out.
  5. 5. a starting substance in a chemical reaction
  6. 11. a variable that can only have a whole-number value