Radioactivity

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Across
  1. 1. high-energy, high-speed electrons or positrons
  2. 4. One of the worst nuclear disastors, in modern day Ukraine
  3. 6. The proccess of the Nucleus of an unstable atom losing energy
  4. 7. An element with a different number of neutrons
Down
  1. 2. Like beta particles, but earlier in the greek alphabet
  2. 3. at the centre of every atom
  3. 5. Bad stuff, avoid it.