Story 2 Crossword

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Across
  1. 1. to spread out
  2. 5. humans selecting offspring with favorable traits to reproduce
  3. 6. any pure substance that we know the composition of the particles
  4. 8. particles in mixture evenly mixed
  5. 12. substances present before chemical reaction
  6. 15. smallest particle of matter
  7. 17. anything that has mass and takes up space
  8. 19. atoms are not created or destroyed in chemical reactions
  9. 21. substance composed of all the same molecule
  10. 22. particles in mixture not well mixed so different parts are visible
  11. 23. one or two letters used to represent an element.
Down
  1. 2. sexual reproduction method of plants
  2. 3. particle made of many atoms bonded together
  3. 4. how heavy the nucleus of an atom is
  4. 7. when particles of different substances rearrange creating new substances
  5. 9. substances composed of many different particles
  6. 10. cut and pasting DNA from one organism to another
  7. 11. number of protons in an atom and is used to identify each element
  8. 13. substances composed of only one particle
  9. 14. substance composed of all the same atom
  10. 16. organized chart showing repeating patterns on known elements
  11. 18. shows the type and number of atoms in a molecule
  12. 19. completely copying DNA of one organism to create a copy
  13. 20. substances present after chemical reaction