the undiscovered element

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Across
  1. 5. chemistry in the field(8)
  2. 6. lazy chemist(5)
  3. 7. a chemist does this on 2 wheels(7)
  4. 9. new HOD(7)
  5. 11. plants do this 24/7(14)
  6. 14. pj does this on his pc(9)
  7. 17. the science dept only has 3(8)
  8. 18. Real Science?(9)
  9. 19. down under devil(3)
  10. 21. never did what it said on the tin(4,7)
  11. 22. Leavers'supper entertainment(7,4)
  12. 24. the first balloon goes off with a bang(8)
Down
  1. 1. from the apothecary(7)
  2. 2. friday afternoon fun(7)
  3. 3. the Queen breathes this(5,3)
  4. 4. 32 not out(7)
  5. 8. recent activity(3,4)
  6. 10. Mr J's favourite Bio topic(12)
  7. 12. dizzy rodent device(7,5)
  8. 13. hornets f.c(7)
  9. 15. exploding infant(5,4)
  10. 16. do this round the backs(7)
  11. 20. not too many planets like ours(4,5)
  12. 23. not a banjo(6)