Radioactivity crossword

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Across
  1. 3. Dense material used to protect people or objects from radiation exposure.
  2. 9. Energy that carries enough power to detach electrons from atoms or molecules.
  3. 10. A positively charged particle found in the nucleus of an atom.
Down
  1. 1. The process by which an unstable atomic nucleus loses energy by emitting radiation.
  2. 2. A device used for detecting and measuring ionizing radiation.
  3. 4. A dense, radioactive metal (atomic number 94) used in nuclear reactors and weapons.
  4. 5. A stable subatomic particle with a negative charge, found outside the nucleus.
  5. 6. The total number of protons and neutrons in an atomic nucleus.
  6. 7. The emission of energy as electromagnetic waves or moving subatomic particles.
  7. 8. The time required for half of the radioactive atoms in a sample to decay.