Chapter 7 Revision Sheet

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Across
  1. 3. The ability to do work
  2. 5. The new substances that are formed during a chemical reaction
  3. 6. Reactions in which a substance reacts with oxygen and heat is released
  4. 8. An ion with a negative charge
  5. 12. The law of … which states that matter can be neither created nor destroyed during a chemical reaction.
  6. 13. What takes place when the bonds between atoms are broken and new bonds are formed, creating a new arrangement of atoms and at least one new substance.
  7. 16. Element represented by the letter K
  8. 18. The number that tells you how many atoms are in a molecule
  9. 19. Complete the equation: methane + oxygen —> _____ ______ + water
  10. 20. Chemical reactions that release energy
  11. 23. Chemical reactions that absorb energy from their surroundings
  12. 24. All chemical equations need to be _______
  13. 25. Combustion reactions are examples of ______ reactions
  14. 26. Complete the equation: hydrogen + _____ —> water
  15. 27. The shell which can hold up to 18 electrons
Down
  1. 1. The protons and neutrons in an atom make up the _____
  2. 2. The original substances in a chemical reaction
  3. 4. The number that tells you how many molecules are in an equation
  4. 7. A change of state is an example of a _____ change
  5. 9. A charged atom
  6. 10. The law of ... which states that a compound, no matter how it is formed, always contains the same relative amounts of each element.
  7. 11. The substance that reacts with oxygen in a combustion reaction
  8. 14. The number of protons on an atom. Determines the element
  9. 15. What Alfred Nobel invented
  10. 17. An atom with a different number of protons and neutrons
  11. 18. The number that tells you the charge of an ion
  12. 21. Number of electrons the first shell can hold
  13. 22. An ion with a positive charge