Unit 1

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Across
  1. 3. smallest particle of an element that maintains the properties of that element
  2. 7. electron(s) located in outer energy level (electron shell)
  3. 9. the positively charged center of an atom containing the protons and neutrons
  4. 11. the vertical columns on the Periodic Table
  5. 13. a pure substance that cannot be broken down chemically into simpler substances
  6. 15. a characteristic of a substance that describes how it combines with other substances to form new ones
  7. 16. a conceptual model in which the elements are organized according to their properties; often displayed as a chart
  8. 17. elements located along the stair step on the PTE that have both metal and nonmetal properties
  9. 18. average mass number of all atoms of an element (from particles in the nucleus)
  10. 19. the negatively charged space containing electrons that surrounds the atomic nucleus
Down
  1. 1. a positively charged particle within the atomic nucleus; used to identify an element
  2. 2. property of matter that can be observed without changing the composition or identity of the matter
  3. 3. the number of protons in the nucleus of an atom; used to determine an element's position in the Periodic Table
  4. 4. total number of protons and neutrons in a specific atom
  5. 5. the horizontal rows on the Periodic Table
  6. 6. the tendency of a substance to undergo chemical changes in a system
  7. 8. a (neutral) particle with no electrical charge within the atomic nucleus
  8. 10. a property of a subatomic particle; positive (protons), negative (electrons), or neutral (neutrons)
  9. 12. a particle smaller than an atom, such as a proton, neutron, or electron
  10. 14. a negatively charged particle in the electron cloud surrounding the atomic nucleus