Element mix-up

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Across
  1. 5. Has an atomic number of 17
  2. 8. Has a total mass of 40 amu (rounded)
  3. 10. Has the lowest electron count of all elements that have 3 valence electrons.
  4. 11. Has the lowest density of alkali metals, as well as the smallest atomic radius.
  5. 12. At temperatures close to absolute zero, it becomes a liquid. Naturally a gas.
  6. 13. Makes up 21% of the Earth's atmosphere, breathed in by humans.
  7. 14. Rhymes with the element above it on the periodic table, is an alkaline earth metal.
  8. 16. Highest melting point of all of the elements, found in gaseous and solid forms naturally.
Down
  1. 1. Atomic symbol is "Si"
  2. 2. 3p4
  3. 3. has an isotope called Tritium, which contains two neutrons and is radioactive.
  4. 4. Used for fertilizer production
  5. 6. The most reactive element of the periodic table
  6. 7. Combines with chlorine to make table salt
  7. 8. Goes before the word "foil", is easily shape-able.
  8. 9. Has no odor, tasteless, and colorless, has the atomic symbol "N"
  9. 10. Group 2 of the periodic table, top of the family
  10. 15. The boiling point of this element is -246 degrees C, naturally occurring as a gas.