1. The building bricks of the world

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Across
  1. 2. A state of matter that is neither liquid nor gas
  2. 4. It is one of the physical properties of matter, together with density
  3. 6. It is made up of two or more chemically bonded elements
  4. 8. A small piece of matter with positive electrical charge
  5. 11. A small piece of matter with a negative electrical charge
  6. 13. The smallest unit of a chemical element
  7. 14. A chemical substance that is made of atoms all of the same kind
  8. 16. A state of matter that is neither liquid or solid
  9. 17. A state of matter that is neither solid nor gas
Down
  1. 1. point The temperature at which a liquid becomes a gas
  2. 3. It includes the study of chemical elements, compounds and chemical reactions
  3. 5. The physical substance the universe is made of
  4. 7. point The temperature at which a liquid becomes a solid
  5. 9. A part of an atom that has no electrical charge
  6. 10. It is a synonym for "state"
  7. 12. The central part of an atom
  8. 15. point The temperature at which a solid becomes a liquid