Finding Formulas from Systematic Names: How Does the Number in Parentheses Help?

[IDK10]

Homework Statement

Sodium chlorate(I)
Sodium chlorate(V)
Potassium nitride(III)
Phosphorus(III) chloride
Magnesium iodate(I)

Homework Equations

None

The Attempt at a Solution

I know the number in the bracket refers to what's before it, i.e. in sodium chlorate(V), the (V) means that the chlorine has an oxidation number of +5, but how does this help me find the fomula of the copound.

For example with sodium chlorate(V):
I know its made from sodium (Na⁺) ions, and chlorate(ClO₃^-) ions.

 

[Borek]

Molecule must be neutral, assume charge on oxygen to be -2.

 

[mjc123]

I'm not familiar with the use of this style for negative oxidation numbers, e.g. potassium nitride(III), if this is really K₃N and not a typo for potassium nitrate(III) = potassium nitrite = KNO₂.

 

[IDK10]

Molecule must be neutral, assume charge on oxygen to be -2.

For sodium chlorate(I)
Na would be +1
Cl would be +1
and O would be -2
1 + 1 - 3(2) = -4 (what would I do with this?)

Or

Na + 1 -6 = 0
Na = 5 (?)

For sodium chlorate(V)
Na would be +1
Cl would be +5
and O would be -2
1 + 5 - 3(-2) = 0
NaClO₃

 

[IDK10]

.

 

[mjc123]

How many oxygens are there in sodium chlorate(I)?
Note: in this nomenclature you must not get hung up on the notion that e.g. "chlorate" means "ClO₃". All oxysalts are "ates" with different oxidation number of the central atom. This is quite different from the "ate", "ite", "per...ate" system.

 

[IDK10]

How many oxygens are there in sodium chlorate(I)?
Note: in this nomenclature you must not get hung up on the notion that e.g. "chlorate" means "ClO₃". All oxysalts are "ates" with different oxidation number of the central atom. This is quite different from the "ate", "ite", "per...ate" system.

I'm not sure, I have to find the formula just from the name. I know sodium chlorate(v) has 3.

 

[Borek]

For sodium chlorate(I)
Na would be +1
Cl would be +1
and O would be -2

And assuming one Na and one Cl, how many oxygens are needed for the molecule to be neutral?

 

[IDK10]

And assuming one Na and one Cl, how many oxygens are needed for the molecule to be neutral?

While I was away, amd therefore didn't see your reply, I was thinking and I think i got it:
1 + 1 -2O = 0
-2O = -2
O = 1
NaClO?

 

[Borek]

While I was away, amd therefore didn't see your reply, I was thinking and I think i got it:
1 + 1 -2O = 0
-2O = -2
O = 1
NaClO?

Yep.

Try with chlorate(III) and chlorate(V).

 

[IDK10]

Yep.

Try with chlorate(III) and chlorate(V).

Sodium chlorate(III):
1+3-2O=0
-2O=-4
O=2
NaClO₂

Sodium chlorate(V):
1+5-2O=0
-2O=-6
O=3
NaClO₃

 

[Borek]

At least with these you should have no problems now