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Is the octet rule, important to the atom?

  1. Jun 6, 2012 #1
    Can an atom "give away" or "steal from another" an electron AND become an ion just to "satisfy" the Octet rule?

    Does an atom "prefer" to have 8 electrons in the outer shell MORE then it "wants" a neutral charge(not be an ion)?

    I imagine this varies from element to element. The elements i am puzzled about is silicon (Si 14) and Germanium.


    (I don't know much chemistry, so be "nice")
     
  2. jcsd
  3. Jun 6, 2012 #2
    The octet rule is really only qualitatively meaningful for 2nd row atoms and for other reasons, halogens, beyond that, exceptions are extremely common and the rule should be applied with care.

    I'm not much of a chemist so I can't comment on Silicon and Germanium specifically.
     
    Last edited: Jun 6, 2012
  4. Jun 6, 2012 #3
    Silicon and germanium are both group 14 elements (right below carbon). So - speaking from a very simple (and naive) application of the octet rule - they'd have to give up or accept four electrons to have a full shell. As a result, they tend to form covalent compounds like carbon, although the likelihood of doing so decreases going from silicon to germanium (silicon, at least, will form siloxanes - silicon bonded to an oxygen and two organic groups - which can then polymerize). I know there is some organogermanium chemistry out there, but I'm not very familiar with it.

    In general, though, the octet rule is kind of misleading. I at least wish they'd rename it the "octet guideline," since once you get to chemistry beyond the second row - which is where most of the periodic table resides - it's not that helpful.

    As an aside....

    If I'm mistaking you for someone else on here, my apologies. But aren't you going to/in grad school for chemistry? If so, I'd say that qualifies you as a chemist.
     
  5. Jun 6, 2012 #4
    Im so sorry, but i realize i got the elements wrong! Im actually wondering about Aluminum and Phosphorus. Sorry about that!

    Im trying to understand semiconductors(in physics), and the answer to this would clear some things. Sorry for wasting time on Si an Germanium, This time I'm sure ;)

    Silicon and germanium is often used as the conductors, but Aluminum and phosphorus is used as "dope" in the conductors. Thats why i asked about Silicon and germanium instead of what i meant to ask about; Aluminum and Phosphors.
     
  6. Jun 6, 2012 #5
    That's me but I'll be doing physical chemistry. I don't have much descriptive/inorganic knowledge. I know very little of chemical reactions and such.
     
  7. Jun 6, 2012 #6
    The standard explanation is that if you - for example - substitute in phosphorus for silicon, phosphorus will make four bonds to four silicon atoms, and the remaining electron will be available for conduction. Conversely, if you substitute in aluminum for silicon, the aluminum will leave a hole since it only has three valence electrons to work with, in contrast to the four that silicon has available. For dealing with semiconductors (or solids of any sort), you're not really looking at individual atoms since these things are delocalized, and you're mostly interested in the band structure and how a donor or acceptor changes that band structure.

    Ahh, OK. I was just thrown for a moment there. It will, however, spare you from the joining the list of people who publish some new reaction and then never seem to follow it up with a proper mechanism paper. It's oh so irritating when I read a paper that promises such a follow-up, but never seems to deliver. Heh.
     
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