Nuclear Radiation

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Across
  1. 3. this consists of two neutrons and two protons, it is the same as a helium nucleus
  2. 5. The number of protons in an atom of an element
  3. 6. The electrons are arranged at different distances from the nucleus
  4. 9. Most of the mass of an atom is concentrated in the...
  5. 10. A random process where an unstable nucleus gives out radiation as it changes to become more stable.
  6. 11. a high speed electron ejected from the nucleus as a neutron turns into a proton
  7. 12. Atoms of the same element can have different numbers of neutrons
Down
  1. 1. the time it takes for the count rate (or activity) from a sample containing the isotope to fall to half its initial level
  2. 2. The total number of protons and neutrons in an atom
  3. 4. The rate at which a source of unstable nuclei decays
  4. 7. electromagnetic radiation from the nucleus
  5. 8. Atoms turn into positive ions if they lose one or more outer