Ask A Scientist Chemistry Archive

name         Garrett
status       student
grade        6-8
location     OH

Question -   Do the oxidation state, charge, and valency of an element 
have anything to do with each other?
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Garret,

You are correct in realizing that these terms are all somehow related. 
Oxidation state and charge are pretty much the same thing, it is a 
statement on the difference between the number of protons and electrons 
found in each atom or ion. Valency is almost the same thing. Valency is 
the number of electrons in the outer shell of an atom and usually tells 
how many electrons may interact with other atoms in forming bonds. Since 
it is the outer electrons that tend to be removed during oxidation, then 
valency is a good way of predicting oxidation states. This is not always 
true, however, but do not focus on the exceptions, focus rather on what 
these terms mean.

Greg (Roberto Gregorious)
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Your question shows a sense of critical thinking I find commendable.
In many cases the terms are just used interchangeably. What they have in
common is an attempt to correlate atomic/molecular structure to some
"intrinsic" property (empirical or theoretical) of the constituent atoms
(oxidation state, charge, valency).             Making the connection
requires several broad "acts of faith" on the part of the student because
in order to hold on to these concepts (which personally I find hopelessly
flawed).
   It is necessary to immediately modify the bonding model(s) with "ad
hoc" after-the-fact patches. Specifically, "resonance structures", "formal
charges", "electron promotion, "valence shell electron pair repulsion (VSEPR)
for short" -- The list is longer but four patches will suffice to make my
point.
     Introductory chemistry as it relates to the chemical bond needs a
conceptual overhaul, but textbook authors seem content, for the most part,
to just copy the ideas from older texts.

Vince Calder
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