Particle nature of matter

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Across
  1. 2. MOLECULES/ They contain two atoms
  2. 4. Has a charge of 0 and it's position is inside the nucleus
  3. 8. Number of electrons in the first shell
  4. 9. Is made up of more than one element, chemically combined
  5. 10. THEORY/ All matter is made of very tiny particles
  6. 11. ISOTOPES/ Isotopes that are unstable that decay over time
  7. 12. The nucleon number of magnesium
  8. 13. Consists of tiny particles and rays and it can destroy body cells and kill you
  9. 14. Are made up of more than one atom
  10. 16. Is the number of proton + neutrons inside the nucleus
  11. 17. Contains atoms of one kind only
  12. 20. The forces between particles are strong or quite strong
Down
  1. 1. ENERGY/ Energy of movement
  2. 3. Are atoms of the same elements but different masses
  3. 5. Some particles gain energy to overcome the forces between them and escape
  4. 6. Is the smallest part of a substance that can exist in it's own
  5. 7. It is inside the nucleus
  6. 15. It's mass is 1/1836u
  7. 18. The particles are still close together
  8. 19. The particles are far apart