Chapter 2 Vocabulary

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Across
  1. 2. any element that spontaneously emits radiation
  2. 5. the sum of the number of protons and neutrons in an atom
  3. 6. the smallest piece of an element that still represents that element
  4. 7. the region surrounding an atom's nucleus where one or more electrons are most likely to be found
  5. 9. a neutral particle in the nucleus of an atom
  6. 12. a process that occurs when an unstable atomic nucleus changes into another more stable nucleus by emitting radiation
  7. 13. atoms of the same element that have different numbers of neutrons
Down
  1. 1. the average mass of the element's isotopes, weighted according to the abundance of each isotope
  2. 3. the number of protons in an atom of an element
  3. 4. positively charged particle in the nucleus of an atom
  4. 8. an atom that is no longer neutral because it has lost or gained valence electrons
  5. 10. a negatively charged particle that occupies the space in an atom as dots around the element's chemical symbol
  6. 11. the region in the center of an atom where most of an atom's mass and positive charge are concentrated