Periodic Table

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Across
  1. 8. A pure substance made of only one kind of atom.
  2. 10. Elements that are dull, poor conductors, and brittle.
  3. 12. Elements with properties of both metals and nonmetals.
  4. 13. Group 1 elements; very reactive, especially with water.
  5. 14. A chart organizing all known elements by atomic number and properties.
  6. 15. Negatively charged particles that orbit the nucleus in energy levels.
  7. 17. Group 17 elements; very reactive nonmetals.
  8. 19. The average mass of an atom of an element.
  9. 21. are columns (same valence electrons);
Down
  1. 1. The scientist who created the first periodic table.
  2. 2. The number of protons in an atom’s nucleus; identifies the element
  3. 3. are rows (same energy levels).
  4. 4. Elements in the second row below the main table, many are radioactive.
  5. 5. Neutral particles found in the nucleus of an atom.
  6. 6. Group 18 elements; very stable and unreactive.
  7. 7. Elements in the first row below the main table, rare earth metals.
  8. 9. Elements in groups 3–12; good conductors, often used in construction.
  9. 11. Group 2 elements; reactive but less than alkali metals.
  10. 16. Elements that are shiny, good conductors, and malleable.
  11. 18. Positively charged particles found in the nucleus of an atom.
  12. 20. One or two letters that represent an element.