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Why is this ion more paramagnetic?

  1. Oct 5, 2005 #1
    Why is [tex]Mn^+[/tex] more paramagnetic than [tex]N,S,Fe^+,Cr^{+2}[/tex]

    I guess the answer would be "because it has 6 unpaired electrons" but why is that? How could I tell in advance that the one electron removed from [tex]Mn[/tex] was the paired one in 4s orbital and not one of the unpaired in 3d? The Energy of 3d is higher than 4s, and it is populated after 4s, so how come you take electrons from there first?

    more generally, when I have a positive ion, how can I tell its electron configuration?

    thanks..
     
  2. jcsd
  3. Oct 5, 2005 #2

    somasimple

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  4. Oct 5, 2005 #3
    No it does not come with the one i'm allowed to use in a test.
    In my table there's only the electron configuration of the standard element, not its ions.
     
  5. Oct 5, 2005 #4

    somasimple

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    Please click on an element in the table and you will have much more information.
     
  6. Oct 5, 2005 #5

    Gokul43201

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    Ahmes,
    This is an excellent question, and the complete answer is mostly beyond the scope of high school/college chemistry.

    Before I attempt any kind of explanation though, I'd like to make sure you have written down the question exactly as it appears in your homework/text/notes. I say this because Mn and Fe are rarely, if ever, found in the +1 oxidation state, so it is meaningless to speak of Mn+ or Fe+.
     
  7. Oct 5, 2005 #6
    Thank you Gokul43201, this is indeed the question as it appeared in a previous test, those are the ions.

    I read in a general chemistry book that Chromium has an exceptional electron configuration [and is supposed to be extremely magnatic :grumpy: I just tried with some (metal which is supposed to be) Chromium in the bath and the fridge's magnets hardly stuck to it]
    The thing is, [tex]Mn^+[/tex] should have the same electron configuration as the element before Manganese, which is Chromium - but it has an exceptional configuration so I don't know whether it applies.

    Thanks again.
     
  8. Oct 5, 2005 #7

    Gokul43201

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    I'll take little bits at a time.

    Cr is not ferromagnetic, and hence will not have any effect at all on a fridge magnet. The only ferromagnetic transition metals are Fe, Co and Ni. Please tell me what this text is that claims that Cr is "extremely magnetic". I'm guessing, it meant to say that Cr is "extremely paramagnetic" - and there's a big difference.

    Cr does have an unusual electronic configuration. At atomic number 24, a naive guess of its config would be [Ar] 4s2 3d4. However, it is found to actually have the configuration [Ar] 4s1 3d5 - one of the 4s electrons is promoted to a 3d orbital. This actually reduces the energy because of the extra stability that comes from half-filled subshells. Now, because of this configuration, Cr has 6 unpaired electrons (just as Mn+ would be expected to as well), making it highly paramagnetic.

    Ferromagnetism comes about from much more than just having unpaired electrons. It depends not only on the properties of the individual atom but also on the interactions between atoms. There is no such thing as a single ferromagnetic atom.
     
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