How do you find the oxidation number of an element?
Answer (3)
the thing you MUST do FIRST is look for any H's, O's, or F's in the equation
1)any element just by itself not in a compound, their oxidation number is 0 ex: H2's oxidation number is 0 ex: Ag: oxidation number is 0 if its just something like Ag + BLA = LALA
the oxidation number of H is always +1, unless its just by itself (see #1)
the oxidation number of O is always -2, unless its just by itself (see #1)
the oxidation number of F is always -1, unless its just by itself (see#1)
ok so after you have written those oxidation numbers in rules 1-4 over each H, F, or O atom in the compound, you can look at the elements that we havent talked about yet
for example:::: N2O4
the oxidation number of O is -2.
since there are 4 O's, the charge is -8. now remember that N2O4 has to be neutral so the N2 must have a charge of +8 +8 divided by 2 = +4
N has an oxidation number of +4.
more rules: 5) the sum of oxidation numbers in a compound add up to 0 (when multiplied by the subscripts!!!) (see above example) 6) the sum of oxidation numbers in a polyatomic ion is the charge (for example, PO4 has a charge of (-3) so
oxidation # of O = -2. (there are 4 O's = -8 charge on that side ) P must have an oxidation number of 5. (-8+5= -3), and -3 is the total charge of the polyatomic ion
Assigning Oxidation Numbers
To find the oxidation number of an element, several rules should be followed. These rules help determine how many electrons have been gained or lost by atoms in a molecule, which in turn reveals the molecule's oxidation state. Knowing the oxidation number is essential in understanding redox reactions without the need for drawing electron dot diagrams.
Atoms in their elemental state are assigned an oxidation number of 0.
Atoms in monatomic ions have an oxidation number equal to the ion's charge.
For common nonmetals in compounds, hydrogen has an oxidation number of +1 unless bonded with metals where it's -1, oxygen is generally -2, and halogens like fluorine are typically -1.
The sum of the oxidation numbers in a compound should equal the molecule's overall charge.
To balance redox reactions, adjustments may be necessary to ensure that the total increase in oxidation number equals the total decrease.
To apply these rules in a practical example, you would assign each element its oxidation number and adjust coefficients in the reaction equation to balance the overall change in oxidation states.
To find the oxidation number of an element, use specific rules for common elements like H, O, and F, along with balancing total charges in compounds. For instance, in N2O4, nitrogen has an oxidation number of +4, while in a polyatomic ion like sulfate, sulfur has an oxidation number of +6. Overall, oxidation numbers help in understanding electron transfer in chemical reactions.
;
