atoms and elements

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Across
  1. 6. a stable subatomic particle with a charge of negative electricity
  2. 7. the lightest element
  3. 8. the basic unit of a chemical element.
  4. 12. A one-or-two letter abbreviation for the element that appears directly below its atomic number on the periodic table
  5. 15. a class of chemical elements they are all odorless, colorless, monatomic gases with very low chemical reactivity
  6. 16. a chemical element with the symbol N and atomic number 7
  7. 17. a subatomic particle of about the same mass as a proton but without an electric charge
  8. 18. combine to form composite particles called hadrons
  9. 19. the smallest discrete amount or quantum of electromagnetic radiation.
  10. 20. positively charged region in the center of an atom
Down
  1. 1. the number of protons and electrons in an atom
  2. 2. a chemical element that forms a salt when it reacts with metal
  3. 3. chemical change reactants
  4. 4. one of two or more species of atoms of a chemical element with the same atomic number and position in the periodic table
  5. 5. minus atomic number is how to find the number of neutrons in an atom
  6. 9. a chemical element with the symbol Ne and atomic number 10
  7. 10. a chemical element with the symbol C and atomic number 6
  8. 11. Substance is made up of two or more atoms in a fixed proportion.
  9. 13. has the same properties at every point
  10. 14. Composed of only one type of Adam, molecule, element