What does fully oxidized mean? [closed]








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I am confused as to the meaning of fully oxidized, in the context of environmental chemistry (what is water soluble). While I believed that CO$\_2$ was fully oxidized after reading <http://hyperphysics.phy-astr.gsu.edu/hbase/Chemical/redoxea.html>, I also read that SO$\_2$ is a reducing agent. Additionally, looking at the electronegativities of carbon versus sulfur, they are the same. Thus, what types of chemicals would fully oxidized refer to?




It comes down to the [oxidation number](http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch2/oxnumb.html) of the element in the compound. From the link you provided, $\ce{CH4}$ has carbon in its most reduced form, with an oxidation number of $-4$. Carbon can't become any more reduced because a $-5$ state would imply that carbon had $9e^-$ in its valence shell, which would be highly unfavorable. Similarly, $\ce{CO2}$ has carbon in its most oxidized form, with an oxidation number of $+4$. Carbon can't become any more oxidized because a $+5$ state would imply that carbon lost an electron from its inner shell, which would be highly unfavorable.


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