Atoms

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Across
  1. 2. a___ is a group of atoms held together?
  2. 3. Atoms with the same atomic # but different atomic masses?
  3. 6. An electron carries a ____ charge?
  4. 10. Sum of protons and neutron in nucleus of an atom?
  5. 12. proton carries a ___ charge?
  6. 13. are composed of atoms in ordered layers.
  7. 15. the horizontal rows of a periodic table.
  8. 17. Posituvely charged particle found in the nucleus?
  9. 18. An __ is electrically charged particle.
  10. 19. A nonmetallic element with the Atomic number 6.
  11. 20. is a column of elements in the periodic table of chemical elements.
Down
  1. 1. Molecules of ___ have atoms of 2 or more different elements.
  2. 4. What can't be decomposed into simpler substances by ordinary?
  3. 5. Mass of an atom is here?
  4. 7. What is the unit of mass for an atom?
  5. 8. What is the smallest particle of an element?
  6. 9. mainly found in the upper right corner of the periodic table.
  7. 11. number - atomic number?
  8. 14. Atoms are made up of 3_______particles?
  9. 16. equal to the # or protons in neutral atom?