Periodic Table intro2

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Across
  1. 3. elements with similar reactivity
  2. 4. arrangement of elements with same number of shells around their nucleus
  3. 7. shortest period
  4. 8. number of shells of ions of chlorine and potassium are similar to it
  5. 9. a noble gas which shows some reactions
  6. 11. an element with last two or three partially filled shells
  7. 12. arranged elements in periods and columns
  8. 14. coinage metals
  9. 17. least reactive alkali metal
  10. 19. colourless, odourless, highly flammable gas with atomic number 1
  11. 20. mutual sharing of an electron pair between two atoms
  12. 22. determines the group number
  13. 25. they have same number of protons but different mass numbers
  14. 27. last element in the periodic table
  15. 29. any substance which cannot be decomposed into simpler substances
Down
  1. 1. Most reactive halogen
  2. 2. a noble metal
  3. 5. total number of families in the periodic table
  4. 6. doeesnot occur in earth's atmosphere
  5. 10. electrostatic attractions between oppositely charged particles
  6. 13. third element in carbon family
  7. 15. has 5 electrons in the 3rd shell
  8. 16. donot contain normal elements
  9. 18. most reactive non metals
  10. 21. a neutral subatomic particle of an atom
  11. 23. metals of group II-A
  12. 24. name given to group 6 A elements
  13. 26. can gain one electron with highest difficulty to form negative ion as compared to other members of its group
  14. 28. abbreviations used in chemistry for chemical elements