Periodic table vocabulary crossword

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Across
  1. 6. a substance made up of only one type of atom
  2. 8. the number of an element on the periodic table; tells how many protons are in an atom of that element Always smaller than the atomic mass.
  3. 10. smallest unit of a particular element
  4. 13. atomic mass rounded to the nearest whole number; tells the number of protons and neutrons combined
  5. 14. a characteristic or description of a substance
  6. 15. gases all the way to the right on the periodic table (called group 0, group VIII, or group 18). Very unreactive because they have a full outer shell (8 valence electrons)
  7. 17. Elements that have properties of both metals and non-metals and are found along the zig-zag line on the periodic chart. Also called semimetals or semiconductors.
  8. 19. a row (horizontal) on the periodic table. Elements in the same period have the same number of energy levels. Properties vary gradually as you go from left to right.
  9. 20. elements the do not conduct electricity, are not shiny and do not conduct heat; found toward the right of the periodic table (except Hydrogen, which is at the top left)
Down
  1. 1. Group I; very reactive, one valence electron
  2. 2. The average mass (number of protons and neutrons) in an atom. Always larger than the atomic number.
  3. 3. the center of an atom; includes protons and neutrons
  4. 4. Group VII/Group 17, very reactive nonmetals, have seven valence electrons
  5. 5. how likely an element is to undergo a chemical change; depends on the number of valence electrons
  6. 7. positive particle found in the nucleus of an atom
  7. 9. A one or two letter abbreviation for an element. The first letter is always capitalized and the second letter is always lowercase.
  8. 11. vertical column on the periodic table. Elements in the same group have the same number of valence electrons and similar chemical properties.
  9. 12. Neutral (zero-charge) particle in the nucleus of an atom
  10. 16. the number of electrons found in the outermost shell
  11. 18. elements that conduct electricity, are shiny, heat well and are easily shaped, solid at room temperature (except mercury); found toward the left of the periodic table