what is the oxidation numbers for P and O in PO4 with a negitive charge of 3...and how did you get it?

Question

what is the oxidation numbers for P and O in PO4 with a negitive charge of 3...and how did you get it

Answer 1

PO4^(3-)
This is the same thing, llike if you would write down, phosphoric acid, H3PO4.
First for H3PO4:
H-atoms have +1 charge in this molecule (allmost allways)
O-atoms have -2 charge in this molecule (except in F2O, peroxides, superoxides and ozonides).
Since the whole molecule needs to have zero charge you calculate:
Three H-atoms will have +3 charge [(3 * +1 = +3)].
Four oxigens will have -8 charge [(4 * -2 = -8)]
That means that P will have:
(+3) + (-8) = (-5)
Then you simply change the sign of the result, which would mean that oxidation number of P is (+5)!

And now for PO4(3-).
Basicaly it is the same thing. As I have said, Oxigens will have (-2) charge each. That means that they will, all together, have -8. Since wee need to see for (3-) anion, just find difference beetwen those two:
(-8) - (-3) = (-5) and change the sign, so you will have (+5). So how do you know that this is correct: Total sum of all charges needs to be equal to the charge of an ion, or equal to zero if it is an electro-neutral molecule.
Just add the charge of all atoms in an ion or molecule and if you have total sum charge equal to the charge of ion or to zero, it is correct.

Answer 2

PO4-3 is a radical

O has a -2 oxidation number by definition, 4 of these = -8, remove 3 for the -3 charge leaves -5, P has an ox. no. of +5 to get a balance

Answer 3

O is -2
P is +5

O is (almost) always -2 (there are a few exceptions, but this is not one of them), as shown on the periodic table. -2 x 4 (4 because there are four of them) is -8.

Since the charge is -3, you need a total positive of 5 (5 + -8 is -3). There is only one P, so the charge of P must be +5, and if you check the periodic table, +5 is one of the possible charges listed for P.

Answer 4

You have turned on the Number Lock function. If you look at the front edge of those keys you will see the numbers there. You need to press the FN key and the num lock key at the same time. On my laptops the F11 key is the num lock, so try that.