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I'm all cofused with oxidation state, oxidation number, and formal charge. Can someone go over how each is different from the others?
Thanks!
Thanks!
Oxidation number, Oxidation state, Formal charge
- Thread starter speedyIs
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speedyIs said:
Formal charge is overall charge on a compound and has no relations to the oxidation numbers. Formal Charge = (Group Number of the Central Atom) - (Non-bonding Electrons) - 0.5(Shared Electrons)
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oxidation state refers to bonds to more or less electronegative atoms. take the central atom, and for each bond to a more e-negative atom, assign a +1, and for each bond to a less e-negative atom, assign a -1. a bond to an atom w/ the same e-negativity (aka same element), assign a 0 (in C(CH3)3, the central carbon has an oxidation state of 0 b/c all four of its bonds are to another carbon atom). for example:
CH3O: so the carbon is bonded to three less e-negative atoms in hydrogen (3 x -1 = -3) and one more e-negative atom in oxygen (1 x +1= +1). so the total oxidation state of the carbon is the sum, or -3 + 1= -2 i believe.
a basic rule of thumb is that the more bonds carbon (its usually carbon that they're considering) has to oxygen, the more its oxidized. for example, the oxygen states of an alkane, alcohol, ketone, and carboxylic acid are in the following order:
alkane < alcohol < ketone < carboxylic acid b/c the # bonds to oxygen carbon has is in the order of alkane (0) < alcohol (1) < ketone (2) < caryboxylic acid (3)
when talking about compounds, look at it and figure out the oxidation state of the central atom last. lets say they give you KClO3-. first things u should see is that there is a net negative charge, so when u add up the individual oxidation states, u should get a "-1". now lets figure it out- oxygen is usually a -2 oxidation state b/c it wants 2 electrons to fill its valence shell unless its bonded to a more e-negative atom (like fluorine), so 3 oxygen is like 3 x -2 = <-6>. now the k potassium atom is usually +1 like the other alkali metals b/c they'll want to lose an electron to get a full valence/noble gas configuration- u only have one K atom, so thats a <+1>. lastly, now figure out what charge the Cl atom (the central one) has to have to get a net -1 charge. "-6" + "+1" + "Cl oxidation state" = "-1". simple math gives u +4, so the oxidation states of K, Cl, and O in order are +1, +4, -2, to give the KClO3 cmpd. a net charge of -1.
CH3O: so the carbon is bonded to three less e-negative atoms in hydrogen (3 x -1 = -3) and one more e-negative atom in oxygen (1 x +1= +1). so the total oxidation state of the carbon is the sum, or -3 + 1= -2 i believe.
a basic rule of thumb is that the more bonds carbon (its usually carbon that they're considering) has to oxygen, the more its oxidized. for example, the oxygen states of an alkane, alcohol, ketone, and carboxylic acid are in the following order:
alkane < alcohol < ketone < carboxylic acid b/c the # bonds to oxygen carbon has is in the order of alkane (0) < alcohol (1) < ketone (2) < caryboxylic acid (3)
when talking about compounds, look at it and figure out the oxidation state of the central atom last. lets say they give you KClO3-. first things u should see is that there is a net negative charge, so when u add up the individual oxidation states, u should get a "-1". now lets figure it out- oxygen is usually a -2 oxidation state b/c it wants 2 electrons to fill its valence shell unless its bonded to a more e-negative atom (like fluorine), so 3 oxygen is like 3 x -2 = <-6>. now the k potassium atom is usually +1 like the other alkali metals b/c they'll want to lose an electron to get a full valence/noble gas configuration- u only have one K atom, so thats a <+1>. lastly, now figure out what charge the Cl atom (the central one) has to have to get a net -1 charge. "-6" + "+1" + "Cl oxidation state" = "-1". simple math gives u +4, so the oxidation states of K, Cl, and O in order are +1, +4, -2, to give the KClO3 cmpd. a net charge of -1.
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