The Periodic Table

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Across
  1. 2. These elements have a full valence shell of electrons.
  2. 5. The first element to be made artificially.
  3. 7. The second most prevalent element in the universe.
  4. 9. The atoms of this element have 12 protons in their nuclei.
  5. 10. This element is known to form up to 10 million different compounds.
  6. 13. The element named after the woman who discovered radioactivity.
  7. 14. Valence electrons determine an element's ________.
  8. 16. The elements were formed by nuclear reactions inside ________.
  9. 17. The rows in the periodic table are called ________.
  10. 19. Uranium was named soon after the discovery of ________.
  11. 20. The first element in the periodic table.
Down
  1. 1. Sodium and Potassium are found in which group of metals?
  2. 3. This is the lightest of all the metals and can easily float on water.
  3. 4. Each element in table is represented by a unique ________.
  4. 6. The shiny silver metal that is liquid at room temperature is ________.
  5. 8. Subtracting the atomic number from the mass number gives you the number of ________.
  6. 11. The columns in the periodic table are called ________.
  7. 12. This element is named after one of the most famous scientists of all time.
  8. 15. Fe is the symbol for which element?
  9. 18. A molecule of water contains 2 hydrogen atoms bonded to one atom of this element.