Across
- 3. the total mass of reactants and products are always the same. what is this called
- 4. these fuels are non renewable
- 6. the minimum energy needed for a reaction to occur
- 7. the element with the symbol 'Na'
- 9. dioxide a gas produced when fossil fuels burn
- 13. the element with the symbol 'Pb'
- 14. all things are made up of these tiny units
- 18. a gas needed for burning
- 19. graphs or diagrams that show the energy changes in a recation
Down
- 1. the element with the symbol 'K'
- 2. reactions that release heat energy to the surroundings
- 5. another word for burning
- 8. there are 3 fossil fuels coal oil and which other
- 10. a sign of a chemical reaction taking place
- 11. substances that react together, shown before the arrow in the equation
- 12. the element with the symbol 'Fe'
- 15. a reaction that is irreversible involves this type of change
- 16. the positive subatomic particle
- 17. a reaction that is reversible involves this type of change
- 20. reactions that take in energy from the surroundings