Science Puzzle

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Across
  1. 2. bond / formed when atoms share two pairs of electrons
  2. 3. / an idea to help the people to understand a concept that they cannot observe directly
  3. 5. / move around outside the nucleus of an atom
  4. 6. / elements in the same vertical column of the periodic table
  5. 7. bond / an attraction between a positive metal ion and the electrons surrounding it
  6. 9. / the center core of the atom
  7. 10. bond / the force that holds atoms together
  8. 13. ion / is made of more than one atom
  9. 14. / elements in the same horizontal row of the periodic table
  10. 15. / two or more substances that are mixed together but not chemical combined
  11. 18. bond / electrons are share unequally
  12. 19. / an neutral particle made of two or more atoms joined by covalent bonds
  13. 22. / tells you the ratio of elements in the compound
  14. 25. bond / share three pairs of electrons
  15. 27. bond / formed when two atoms share electrons
  16. 28. electrons / they are in the highest energy level
  17. 30. / the smallest particle of an element
  18. 31. / cannot be broken down into any other substance by chemical or physical means
Down
  1. 1. / is called family
  2. 2. / material that can be pulled out into a long wire
  3. 3. / used to describe a material that can be hammered or rolled into shape
  4. 4. compound / compound that is composed of molecules
  5. 8. metal / element belonging to group 1 of the periodic table
  6. 9. bond / electrons are shared equally
  7. 11. / occupies space
  8. 12. theory / explains and connects wide range of observations
  9. 16. compound / consist of a positive and negative ions
  10. 17. gas / is found in the group 18 in the periodic table
  11. 20. / has the properties of a metal
  12. 21. / particles that are found in the nucleus of an atom
  13. 22. / used to identify an element
  14. 23. / an orderly three dimensional pattern of ions or atoms share electrons
  15. 24. / an atom or group of atoms that has become electrically charged
  16. 26. / an element belonging to group 17of the periodic table
  17. 29. number / protons in the nucleus of an atom
  18. 31. level / a region of an atom in which electrons of the same energy are likely to be found