Chemistry

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Across
  1. 2. The central part of an atom containing protons and neutrons (6)
  2. 5. A mixture where one substance is dissolved in another (8)
  3. 10. Process where a substance changes from a gas to a liquid (10)
  4. 11. The type of bond formed when electrons are shared between atoms (7)
Down
  1. 1. The negatively charged particle that orbits the nucleus (8)
  2. 3. Substance composed of two or more elements chemically combined (4)
  3. 4. The smallest unit of an element that retains its chemical properties (4)
  4. 6. Crossword — 9th Grade
  5. 7. A horizontal row in the periodic table (3)
  6. 8. A positively charged ion (4)
  7. 9. Key (for teacher) Across
  8. 12. The number of protons in an atom's nucleus; defines the element (6)