Atoms and Elements

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Across
  1. 3. Time required for 1/2 of the atoms to decay
  2. 5. Isotopes that are unstable
  3. 7. Horizontal rows of the periodic table
  4. 9. In the nucleus;has a positive charge;mass of 1
  5. 10. Vertical columns of the periodic table
  6. 14. Beta particle is the same size as an electron
  7. 15. Substance that is entirely one type of atom
  8. 16. Indicates the number of protons+neutrons
  9. 17. Outside the nucleus;negative charge; no mass
  10. 19. Has properties of metals and nonmetals
Down
  1. 1. High in energy, does not change the mass
  2. 2. Alpha particle is the same size as the nucleus
  3. 4. Lighter nuclei combine to form heavier nucleus
  4. 6. Brittle, dull, poor conductors
  5. 8. When there is a difference in neutrons
  6. 11. Indicates the number of protons/electrons
  7. 12. In the nucleus;no electrical charge;mass of 1
  8. 13. Large nucleus splits into smaller pieces
  9. 16. Smallest unit of an element that has elemental properties
  10. 18. Make up protons and neutrons