Oxidation numbers

[Katryn Heine 3A]

Is there a difference between oxidation number and charge? How do you know the oxidation numbers of atoms like Cl and Oxygen?

[Caleb_Mei_1J]

Hey Katryn!

Charge is found in ions when there is a transfer of electrons. For instance, if an atom loses an electron, it has a positive charge and if it gains an electron, it has a negative charge. On the other hand, oxidation number is used when there is a sharing of electrons. With oxidation numbers, you essentially make the assumption that the atom either takes bonding electrons, in which it would have a negative oxidation number, or loses bonding electrons, in which case it would have a positive oxidation number.

I hope this helps!

[Jonathan Shyu 3L]

Adding on, specific oxidation numbers are set, such as chlorine, fluorine, or sodium. However, there are elements non in group 1 or 2 or the other rules that require a bit of calculation to determine the oxidation number which is the transition metals. The metals have to be put into a compound and from there, based on what the transition metals are sharing electrons with, the oxidation number can be found.

[Justin_Choo_3J]

Hello!!

Charge is one of the factors used to determine the oxidation number of an element in a compound. Suppose you want to find the oxidation number of the carbon atom in CO2. You would set up the equation with respect to each constituent element: x + -2(2) = 0, in which x refers to the value we are looking for (oxidation number of C), -2 refers to the charge of an oxygen atom (find using the periodic table), the 2 within the parenthesis accounts for the fact that there are 2 oxygen atoms, and the 0 on the left side of the equation denotes that the overall charge of the compound is neutral (if the compound was not neutral, the left side of the equation would equate to the value of the overall charge [-2 in the case of SO4^2-]). Therefore, the oxidation number of C in CO2 is +4.

[Justin_Choo_3J]

Hello!!

Charge is one of the factors used to determine the oxidation number of an element in a compound. Suppose you want to find the oxidation number of the carbon atom in CO2. You would set up the equation with respect to each constituent element: x + -2(2) = 0, in which x refers to the value we are looking for (oxidation number of C), -2 refers to the charge of an oxygen atom (find using the periodic table), the 2 within the parenthesis accounts for the fact that there are 2 oxygen atoms, and the 0 on the left side of the equation denotes that the overall charge of the compound is neutral (if the compound was not neutral, the left side of the equation would equate to the value of the overall charge [-2 in the case of SO4^2-]). Therefore, the oxidation number of C in CO2 is +4.

[Chris Korban 1D]

Charge usually refers to if an atom loses or gains an electron and it is used to indicate an excess or lack of electrons, however oxidation state refers to more of a sharing of electrons and can be found using the element's location on the periodic table. Oxygen has oxidation state of 2- because its in row 16 and would need 2e- to be able to fill its octet. Chlorine is in row 17 and needs 1 e- and therefore has an oxidation state of 1-