Biology Crossword Chap 2

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Across
  1. 4. subatomic particle with a positive charge
  2. 5. subatomic particle with no charge
  3. 9. the sharing of one pair of electrons
  4. 12. the energy that matter has because of its location or structure
  5. 13. Two or more atoms held together by covalent bonds
  6. 14. an atom's total mass
  7. 15. the outermost electron shell
  8. 18. Elements needed by an organism to live a healthy life and reproduce
Down
  1. 1. the sharing of a pair of valence electrons by two atoms
  2. 2. A substance consisting of two or more elements in a fixed ratio
  3. 3. elements that are required in only minute quantities
  4. 6. the smallest unit of matter that still retains the properties of an element
  5. 7. are two atomic forms of an element that differ in number of neutrons
  6. 8. where electrons are found
  7. 10. Anything that takes up space and has mass.
  8. 11. the first element on the periodic table
  9. 16. subatomic particle with a negative charge
  10. 17. the table where all known elements are charted
  11. 18. the capacity to cause change
  12. 19. A substance that cannot be broken down into other substances by chemical reactions