Question
Fri March 21, 2014 By: Ishmeet Kaur Sidana

What are valence electrons?  What is the number of valence electrons in Cl ion.?

Expert Reply
Mon March 24, 2014
  • Valence electrons are the total number of electrons present in the valence shell or outermost shell.
  • The atomic number of chlorine is 17.
  • The electronic configuration is 2, 8, 7.
  • Hence, there are 7 electrons in the valence shell of chlorine.
  • Chlorine it accepts an electron to form a chloride ion as follows:

          Cl + e- → Cl-

  • On accepting an electron, chlorine forms chloride ion which has one electron more than chlorine atom.
  • Thus, the electronic configuration of chloride ion becomes 2, 8, 8.
  • Hence, there are 8 electrons in the valence shell of  Cl- ion.
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