Matter and the Periodic Table Puzzle

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Across
  1. 3. I am one of the noble gases.
  2. 8. I am a transition metal with 47 electrons used to make photographic film.
  3. 10. I am negatively charged and barely contribute to the mass of the atom.
  4. 11. Another name for a column of the periodic table.
  5. 12. I have definite shape and volume.
  6. 14. If phosphorus gains 1 proton it turns into this element.
  7. 15. My atomic number is 7.
  8. 17. I have no charge and you can find me at the center of an atom.
  9. 18. Arsenic is an example of this type of element.
  10. 19. These types of elements are malleable, ductile and conduct electricity.
  11. 21. Two forms of the same element that contain same number of protons but different number of neutrons.
  12. 22. I can be either heterogeneous or homogeneous.
  13. 23. Another name for a row of the periodic table.
  14. 24. I am the heaviest alkaline earth metal.
Down
  1. 1. I am made up of hydrogen and oxygen atoms and you need me to live.
  2. 2. Elemental symbol for tin.
  3. 4. Members of Group 17 (or VIIA) are called _______.
  4. 5. I am the positively charged center of an atom.
  5. 6. My atomic mass is 63.546 amu.
  6. 7. A combination of two or more atoms held together in a specific shape by attractive forces.
  7. 8. You can find me in Group 1 of the periodic table and in table salt.
  8. 9. Electrons furthest from the nucleus that are responsible for interactions of atoms with one another also referred to as _________ electrons.
  9. 13. The number of _______ gives the identity of an element.
  10. 14. Protons, neutrons and electrons are classified as ________ particles.
  11. 16. Substance that contains more than one element.
  12. 20. I take the shape of the container I am in.
  13. 25. An atom that has gained or lost one or more electrons.