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Homework Help: Valence electrons of a transition element

  1. Dec 29, 2011 #1
    Valence electrons of a transition element....

    Here is the electron config. for Iron (Fe) 1s2 2s2 2p6 3s2 3p6 4s2 3d6. I have two questions about this I've been on for hours....

    #1 Which subshell (4s or 3d) has the highest subshell?
    -You can say that the 3d has higher energy because you write it out later than the 4s (4s is filled before 3d)
    -Then again, you can say that the 4s has higher energy because (4, the coefficient, tells us we are in the 4th energy level). 4 is the highest coefficient in that configuration, so the fourth energy level is the outermost.

    So which should I follow - the first or the second?

    #2 I have been also having trouble finding valence electrons for transition elements
    In that configuration I displayed do we say that the valence electrons for Fe is 2? If so, will it always be in the sub shell of the highest coefficient (energy lvl). If I'm not mistaken this means to find the valence of a transition element you will look at the "s" subshell? BUT, since it is in the d-block it has filled the s, so the s will always be 2 for transition elements, so they all have 2 valence electrons?

    Any help would be appreciated :)
  2. jcsd
  3. Dec 30, 2011 #2
    Re: Valence electrons of a transition element....

    Electrons are filled according to The Aufbau's principle ie n+l rule (small L not 1)

    the orbital with higher value of n+l has higher energy and is filled later
    l = 0 for s
    l = 1 for p
    l = 2 for d
    l = 3 for f
  4. Dec 30, 2011 #3
    Re: Valence electrons of a transition element....

    Well my knowledge might be wrong for this one but i think that valance electrons are no. of electrons in outermost energy level

    i.e if configuration was 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p4

    so valence electrons will be 6 (2 in 4s and 4 in 4p)

    (do you know what is wrong about confi.: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5 ??? :biggrin: think about it)
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