Across
- 1. A change that is reversible, in which new substances are not made. Examples of physical changes include changes of state, and dissolving.
- 3. a material that releases energy when it burns
- 6. a change in which energy is absorbed from the surroundings
- 7. Possible source of danger
- 8. A change in which atoms are rearranged to create new substances.
- 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'
- 10. A chemical change in which a substance combines with oxygen, for example; when iron oxidises, forming rust
- 11. A chemical reaction that breaks down compounds into simpler products.
- 12. A rapid reaction between oxygen and fuel that results in heat and light
- 13. a change in which energy is released to the surroundings
- 14. The chance of damage or injury from a hazard
Down
- 1. a substance that forms in a chemical reaction
- 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. 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. Resources that cannot be replenished at rate they are used. The will one day run out.
- 5. a starting substance in a chemical reaction
- 11. a variable that can only have a whole-number value