4th quarter EXAM review 1 of 4

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Across
  1. 3. an electron that is found in the outermost shell of an atom and determines the atom's chemical properties
  2. 5. the mass of an atom expressed in atomic mass units
  3. 6. discovered positively and negatively charged particles in atoms and named the negatively charged particles electrons
  4. 9. one of the elements of group 17 of the periodic table, they combine with most metals to form salt
  5. 10. has 6 electrons in the outermost level and very reactive also includes sulfur in the group
  6. 11. describes something that occurs or repeats at regular intervals
Down
  1. 1. when objects that have the same charge reprel each other, while objects with opposite charges attract each other
  2. 2. the number of protons in the nucleus of an atom
  3. 4. one of the elements of group 13 having 3 electrons in the outer level of each element of this group
  4. 7. discovered there were no path's between levels of electrons, so electrons can jump from a path at one level to antother
  5. 8. a vertical column of elements in the periodic table; elements in this column share chemical properties