uncreative puzzle title

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Across
  1. 2. Contributes to the explosion in nuclear bombs
  2. 4. Used to make weapons of mass destruction
  3. 7. The resistance of getting scratched or damaged
  4. 9. Heat is transferred by movement of a heated fluid
  5. 12. Energy that comes from the sun
  6. 13. The 4th state of matter
  7. 14. How fast something is
  8. 15. A number of things in a certain area
  9. 17. Notorious for the amount of radiation it produces
  10. 19. The building block of all matter
Down
  1. 1. Something that lets heat flow through it
  2. 3. Temperature at which a liquid boils
  3. 5. Used in power plants
  4. 6. 0 The point where all atoms in matter do not move
  5. 8. An atom or molecule that has 1 or more positive or negative charge
  6. 10. The smell something gives off
  7. 11. Particles have these to show its place in an atom
  8. 12. Energy that comes from a source and comes from space that travels at the speed of light
  9. 16. The state of a body that is at rest or in a constant unchanging motion
  10. 18. Something that keeps heat in