Chemical Forums
Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: neepu on October 31, 2010, 10:39:00 PM
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Does anybody know the explanation of why Nb has the unusual electronic configuration?
Nb [Kr]5s1 4d4
Why not Nb [Kr]5s2 4d3
Thanks in advance.
Neepu
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There is more repulsion between paired electrons.
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@Trave11er : Then why does Zr have [Kr]4d2 5s2?? Why not [Kr]4d3 5s1?? I don't want to get into details (which may not be very convincing), but I do know that Nb is just another exception to the general rule of the thumb. The rule doesn't have to apply everywhere...
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Its an exception to the normal filling of electron.
In case of Nb atomic number 41, the above given configuration occurs because:
the energy of 4d and 5s are nearly equivalent( emphasize on the word equivalent)
lets apply the (n+l) rule which gives 4d more energetic and 5s less but due to the diffused activity of 4th shell and d orbital the energy becomes equivalent and the observed electronic config: occurs.
n+l rule for 5s n=5 and l=0( for S orbital) so the value comes 5+0=5
n+l rule for 4d n=5 and d=2 ( for d orbital) so the value comes 4+2=6
5s1,and 4d4 occurs because they are almost same in energy , the experimental results of orbital energy diagram show less difference in energy between 5s and 4d in case of Nb.