Chemistry

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Across
  1. 3. Levels: Energy levels (also called electron shells) are fixed distances from the nucleus of an atom where electrons may be found.
  2. 7. the central part of an atom that comprises nearly all of the atomic mass and that consists of protons and neutrons.
  3. 9. Chemistry is the scientific discipline involved with elements.
  4. 10. the basic unit of a chemical element.
Down
  1. 1. Electron: a valence electron is an outer shell electron that is associated with an atom.
  2. 2. the proton is a positive electric charge.
  3. 4. reaction: a process that involves rearrangement of the molecular or ionic structure of a substance, as opposed to a change in physical form or a nuclear reaction.
  4. 5. a stable subatomic particle with a charge of negative electricity.
  5. 6. a subatomic particle of about the same mass as a proton but without an electric charge.
  6. 8. Cloud: An electron cloud is ​the region of negative charge surrounding an atomic nucleus that is associated with an atomic orbital.