Atoms and the Periodic Table

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Across
  1. 5. The center of an atom that holds protons and neutrons
  2. 6. A particle in the nucleus with no charge
  3. 8. The total mass of protons and neutrons in an atom
  4. 10. A small packet of energy or matter
  5. 11. The letters and numbers that show what an element or compound is made of
  6. 13. A positively charged particle in the nucleus
  7. 16. The smallest unit of matter that makes up elements
  8. 17. A model you can see or touch that represents something
  9. 19. A tool that separates light into a spectrum of colors
  10. 20. A number that describes the location and energy or matter
  11. 22. The number of protons in an atom
  12. 23. A row on the periodic table
  13. 24. A drawing that shows valence electrons around an element's symbol
Down
  1. 1. A chart that organizes all known elements by their properties
  2. 2. A particle in the nucleus, typically a proton or neutron
  3. 3. A full outer electron shell that makes an atom stable
  4. 4. An electron in the outer shell of an atom that's used for bonding
  5. 7. Atoms of the same element with different numbers of neutrons
  6. 8. The one or two letter abbreviation for an element
  7. 9. A pure substance made of only one kind of atom
  8. 12. The pattern of light given off by an element
  9. 14. A model explained with ideas or diagrams, not physical objects
  10. 15. A tiny, negatively charged particle that orbits the nucleus
  11. 18. A column of the periodic table with elements that share properties
  12. 21. A model showing electrons orbiting the nucleus in shells