vocab

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Across
  1. 1. the total number of protons and neutrons in a nucleus.
  2. 4. the mass of an atom of a chemical element expressed in atomic mass units.
  3. 5. atoms as a source of nuclear energy.
  4. 7. a unit of mass used to express atomic and molecular weights,
  5. 10. a part or aspect of something abstract, especially one that is essential or characteristic.
  6. 11. the fixed amount of energy that a system described by quantum mechanics
Down
  1. 2. any of numerous subatomic constituents of the physical world that interact with each other
  2. 3. A group of electrons circulating around a nucleus or a molecule.
  3. 6. the number of a chemical element in the periodic system
  4. 8. the central and most important part of an object, movement, or group, forming the basis for its activity and growth.
  5. 9. the total after taking account both positive and negative charges.