Module 3 The Structure of the Atom

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Across
  1. 6. a neutral, subatomic particle in an atom's nucleus that has a mass nearly equal to that of a proton
  2. 9. radiation that originates from the cathode and travels to the anode of a cathode-ray tube
  3. 11. one-twelfth the mass of a carbon-12 atom
  4. 12. the number of protons in an atom
  5. 16. the smallest particle of an element that retains all the properties of that element; is electrically neutral, spherically shaped, and composed of electrons, protons, and neutrons
  6. 17. radiation that is made up of beta particles; is deflected toward a positively charged plate when radiation from a radioactive source is directed between two electrically charged plates
  7. 18. states that matter is composed of extremely small particles called atoms; atoms are invisible and indestructable; atoms of a given element are identical in size, mass, and chemical properties; atoms of a specific element are different from those of another element; different atoms combine in simple whole-number ratios to form compounds; in a chemical reaction, atoms are separated, combined, or rearranged
  8. 20. a particle with two protons and two neutrons, with a 2+ charge; is equivalent to a helium-4 nucleus, can be represented by a; and is emitted during radioactive decay
  9. 21. atoms of the same element with different numbers of neutrons
  10. 22. a type of equation that shows the atomic number and mass number of the particles involved
Down
  1. 1. high-energy radiation that has no electrical charge and no mass, is not deflected by electric or magnetic fields, usually accompanies alpha and beta radiation, and accounts for most of the energy lost during radioactive decay
  2. 2. a reaction that involves a change in the nucleus of an atom
  3. 3. radiation that is made up of alpha particles; is deflected toward a negatively charged plate when radiation from a radioactive source is directed between two electrically charged plates
  4. 4. a subatomic particle in an atom's nucleus that has a positive charge of 1+
  5. 5. a negatively charged, fast-moving particle with an extremely small mass that is found in all forms of matter and moves through the empty space surrounding an atom's nucleus
  6. 7. the process in which some substances spontaneously emit radiation
  7. 8. a spontaneous process in which unstable nuclei lose energy by emitting radiation
  8. 10. the weighted average mass of the isotopes of that element
  9. 13. a high-speed electron with a 1- charge that is emitted during radioactive decay
  10. 14. energy that comes from a source in the form of waves or particles
  11. 15. the extremely small, positively charged, dense center of an atom that contains positively charged protons and neutral neutrons
  12. 19. the number after an element's name, representing the sum of its protons and neutrons