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Science Forum Index » Chemistry Forum » Valence Electrons
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| Carl Wright |
 Posted: Sat Jan 03, 2004 9:39 pm |
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The number of valence electrons in an element is generally a
"no-brainer" (at least for main group elements). Sodium has one,
chlorine has seven and xenon has eight. However a question I saw
somewhere has me intrigued. How many valence electrons does iron
have? If the definition of valence electrons is the number of "outer"
electrons, the answer would be two, the 4s electrons. If the
definition is the number used for bonding, the valence electrons would
be different for Fe 2+ and Fe 3+. Which do you think is correct?
Carl |
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| Repeating Rifle |
| Posted: Sat Jan 03, 2004 10:53 pm |
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in article 72fdef69.0401031839.52bf602@posting.google.com, Carl Wright at
carlewright@hotmail.com wrote on 1/3/04 6:39 PM:
Quote: The number of valence electrons in an element is generally a
"no-brainer" (at least for main group elements). Sodium has one,
chlorine has seven and xenon has eight. However a question I saw
somewhere has me intrigued. How many valence electrons does iron
have? If the definition of valence electrons is the number of "outer"
electrons, the answer would be two, the 4s electrons. If the
definition is the number used for bonding, the valence electrons would
be different for Fe 2+ and Fe 3+. Which do you think is correct?
Carl
Why isn't the valence for Xe 0 rather than 8?
Valence is not hard and fast. I can picture situations where you have a
mixture of say ferrous and ferric substances where the ratio is determined
by the environment. Temperature, pH, or the presence of oxidizing and
reducing substances can have an effect to change iron valence. Pauling
resonance theory, backed up with more formal quantum theory, should support
such a concept.
For an iron ion, for example, there will be a probability amplitude to be
divalent and another for being trivalent with a mobile electron. There will
be other amplitudes for less probable formations, but they will be much
smaller.
Bill |
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| Douglas Scot Gillman |
| Posted: Sun Jan 04, 2004 5:37 am |
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Good post Carl. I look forward to the discussion.
Doug Gillman
PO Box 16237
Elmwood Place, OH 45216-0237
513-242-2393
Dream on nacelles' wind, Caught in tepid Tome, an urge,
Gin in from the cold. |
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| Aubrey McIntosh |
| Posted: Mon Jan 05, 2004 10:56 am |
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carlewright@hotmail.com (Carl Wright) wrote in message news:<72fdef69.0401031839.52bf602@posting.google.com>...
Quote: The number of valence electrons in an element is generally a
"no-brainer" (at least for main group elements). Sodium has one,
chlorine has seven and xenon has eight. However a question I saw
somewhere has me intrigued. How many valence electrons does iron
have? If the definition of valence electrons is the number of "outer"
electrons, the answer would be two, the 4s electrons. If the
definition is the number used for bonding, the valence electrons would
be different for Fe 2+ and Fe 3+. Which do you think is correct?
Carl
Try using the definition that valence electrons are all of the
electrons beyond the previous inert gas electron configuration. |
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| Bouillote |
| Posted: Mon Jan 05, 2004 1:46 pm |
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Aubrey McIntosh wrote:
Quote: carlewright@hotmail.com (Carl Wright) wrote in message
news:<72fdef69.0401031839.52bf602@posting.google.com>...
The number of valence electrons in an element is generally a
"no-brainer" (at least for main group elements). Sodium has one,
chlorine has seven and xenon has eight. However a question I saw
somewhere has me intrigued. How many valence electrons does iron
have? If the definition of valence electrons is the number of
"outer"
electrons, the answer would be two, the 4s electrons. If the
definition is the number used for bonding, the valence electrons
would
be different for Fe 2+ and Fe 3+. Which do you think is correct?
Carl
Try using the definition that valence electrons are all of the
electrons beyond the previous inert gas electron configuration.
The definition I know is:
The electrons of the last layer (a layer is caraterized by "n", layer
1,2,3....) _and_ the electrons of all the "under layers" ( a "under layer"
is caracterized by "l", 2p,5s,3d are "under layers") not totally full
so for O: 1s2 2s2 2p4 the last layer is for n=2 so there is 4+2=6
then for Fe 1s2 2s2 2p6 3s2 3p6 4s2 3d6 the last layer is 4 so we have 2
electrons and the "under" layer not totally full is the 3d so we have 6+2=8
For Fe2+ []3d6 =>6
For Fe3+[]3d5 =>5
Sorry² for my very bad english |
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