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    Hi, two questions(or three exactly),

    1) How do the binding energies of atomic orbitals in hydrogen-like ions(hydrogenic atoms) vary with the principal quantum number n? Give an example where this hydrogenic sequence of binding energies is violated by the order in which orbitals are filled in building up the Periodic Table.
    What I think is that, binding energy is how strong the nucleus holds the electrons. As n increases, there are more shells present, hence valence electron shielded from nucleus by inner electrons, hence weaker binding energies.

    Binding energies, i think, has a direct implication on first ionisation energies. The pattern might break down between Be and B as well as between N and O.


    2) Given values of the orbital energies of the 2s and 2p orbitals of B4+ and B,

    B4+ 85.0 eV for both 2s and 2p
    B 14.0 eV for 2s and 8.3 eV for 2p

    Account for the electronic configuration of the ground state of B.

    These are questions from the past papers, and many other questions bear similarities with these ones. Please, if you could see if my reasoning for question 1 was true and also, I don't really get question 2. Thanks.
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    For the first part of number 1 it's just about the increasing distance from the nucleus there are no electrons to shield you from the nuclues. But in the second part I'm unsure on - as energy only varies with n then the value of l doesn't matter.

    For two I think the differing energies in B are a result of the extra electrons - shielding from the nucleus, electron pair repulsion etc. They are the same for B4+ because energy only varies with n in hydrogenic systems.
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    (Original post by EierVonSatan)
    For the first part of number 1 it's just about the increasing distance from the nucleus there are no electrons to shield you from the nuclues. But in the second part I'm unsure on - as energy only varies with n then the value of l doesn't matter.

    For two I think the differing energies in B are a result of the extra electrons - shielding from the nucleus, electron pair repulsion etc. They are the same for B4+ because energy only varies with n in hydrogenic systems.
    Hydrogenic atoms can include like C6+ right? so that means it loses all the six electrons its ground state atom has, but the p orbitals are still there, but there are no effect on the binding energy, or is there? atomic radii of C6+ would it be larger than H then?

    For question 2, I am still kinda confused. So, the same values for B4+ implies that energy only varies with n in hydrogenic systems then? so in hydrogenic atoms, could i say that since in B4+, the valence electron would be the one in the s orbital. hence it is much tightly held(the coulomb force, effective nuclear charge, etc), hence the very much larger value compared to the 2s or 2p for just B atom?

    I still don't really understand how all that is supposed to help me account for the configuration of the ground state of B.

    Thanks.
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    C5+ is an hydrogenic ion (C6+ has no electrons) and we can assume its ground state is 1s1 for all hydrogenic systems. The radii of C5+ should be smaller than H as the nuclear charge is much stronger.

    I'm not sure what the second question is getting at either.
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    (Original post by EierVonSatan)
    C5+ is an hydrogenic ion (C6+ has no electrons) and we can assume its ground state is 1s1 for all hydrogenic systems. The radii of C5+ should be smaller than H as the nuclear charge is much stronger.

    I'm not sure what the second question is getting at either.
    Anyway thanks, i had my first taste at organic chem lab work today, 5 hours! and tomorrow the same thing again....lol.
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    (Original post by shengoc)
    Anyway thanks, i had my first taste at organic chem lab work today, 5 hours! and tomorrow the same thing again....lol.
    Only five? It should have been nearer six...
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    (Original post by cpchem)
    Only five? It should have been nearer six...
    hehe, tough work, the senior demonstrator(i think that was what he should be called) was like real angry at three guys who literally turned up so late.

    so any ideas on how to answer the questions above.
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    (Original post by cpchem)
    Only five? It should have been nearer six...
    The last one was a question, any ideas you could help me with my inorganic questions please?
 
 
 
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