# how do i suggest the formula for sodium chlorate (vii) ??

apparently it's NaCl04 but why?? and how??
because the oxidation state of chlorine in the compound is +7. The roman numericals in brackets always states the oxidation state of a certain element in a compound which in this case is chlorine
bluemax
because the oxidation state of chlorine in the compound is +7. The roman numericals in brackets always states the oxidation state of a certain element in a compound which in this case is chlorine

taa. thanks a lot!!! xD
bluemax
because the oxidation state of chlorine in the compound is +7. The roman numericals in brackets always states the oxidation state of a certain element in a compound which in this case is chlorine

The certain element is the one with the variable oxidation state
Original post by bluemax
because the oxidation state of chlorine in the compound is +7. The roman numericals in brackets always states the oxidation state of a certain element in a compound which in this case is chlorine

sorry but can you expand on that...
how do you know the on 7 is referring to the sodium and not the other elements and now that it is 7.....why does it mean the formula is NaClO4
thanks
Original post by Mahfuz1993
sorry but can you expand on that...
how do you know the on 7 is referring to the sodium and not the other elements and now that it is 7.....why does it mean the formula is NaClO4
thanks

The numeral usually goes straight after what it refers to, so if it was sodium it'd be sodium (VII) chlorate. For this, you have sodium = +1 -> chlorate = -1, and with chlorine = +7 you can work out the number of oxygens you need.
Original post by Zygroth
The numeral usually goes straight after what it refers to, so if it was sodium it'd be sodium (VII) chlorate. For this, you have sodium = +1 -> chlorate = -1, and with chlorine = +7 you can work out the number of oxygens you need.

sorry im a bit dumb....so if the roman numerical is the ON for the element its straight after...shouldnt it be for O......basically can you just explain this whole thing..thanks alot!
Original post by Mahfuz1993
sorry im a bit dumb....so if the roman numerical is the ON for the element its straight after...shouldnt it be for O......basically can you just explain this whole thing..thanks alot!

Hmm... the numeral is for the "bit" that's right before it, so in this case it's for "chlorate" rather than "sodium". Then it's just you knowing that chlorate = Cl + O, and O can't possibly be in the +7 oxidation state.
thanks kids
So I understnad that chlorate is always Cl and O. Chlorate (VII) tells me that the oxidation state is +7, but the charge is overall -1. Na is always +1, so surley I ahve +7 +1 =+8, so surely I need to then -9 to get overall -1. I don't get it?
Also if it was NaClO4, and said Na is +1, Cl is +7, and oxygen is -2 (-2x4=-8). surely then the overal charge cancels out to be zero. so doens't have an overall charge on -1?
Original post by kljklj
Also if it was NaClO4, and said Na is +1, Cl is +7, and oxygen is -2 (-2x4=-8). surely then the overal charge cancels out to be zero. so doens't have an overall charge on -1?

The -1 charge is for the chlorate (VII) ion alone. +7 from Cl and -8 from O produces a -1 charge.
Then, to make the neutral compound sodium chlorate, the Na balances it with a +1 charge
Chlorine can exhibit variable oxidation states of -1, 0, 1, 3, 5 & 7.

Chloride oxidation state -1 e.g. NaCl
Chlorine oxidation state 0 e.g. Cl2
Chlorate(I) oxidation state +1 e.g. NaClO - also called sodium hypochlorite
Chlorate(III) oxidation state +3 e.g. NaClO2 - also called sodium chlorite
Chlorate(V) oxidation state +5 e.g. NaClO3 - also called sodium chlorate
Chlorate(VII) oxidation state +7 e.g. NaClO4 - also called sodium perchlorate