Need Help With Some Chemistry plz.. =/?

Question

ok, so..I'm trying to name the following ionic compounds: [All the numbers in these ionic compounds are subscripts]]

A.) NI3(PO4)2
B.) FeI2
C.) MnF3
D.) CrCI2
E.) NaCN

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One example that we took in our notes is:

Write the name of CuO
* Needs the charge of Cu
* O is -2
* Copper must be +2
* Copper (II) Oxide
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Ok, so i sort of get it. I mean, with this example that I followed, I got this: CuS would be Copper (II) Sulfide. Can someone please explain how to do this a little more clearly? thnx

Answer 1

this stuff is so easy

a) Ni (III) Phosphate
b) Iron (II) iodide
c) Mn (III) Fluoride
d) Cr (III) chloride
e) Sodium Cyanide

the (III) (II) are roman numerals (they are only used for transitive metals the middle part of the table)

Answer 2

Ok, if you look at the periodic table you will see that Cu can have more than one charge. One of the possible charges that it can have is 2+, ok so you know that O always has 2-, so because it is Cuo without any number, for example Cu3O ( 3 on the bottom) it means that Cu and O should have the same charge but with opposite signs so that they can cancel each other out. It's Cu second means that the charge is 2, so basically it indicates the charge. It's really easy you just have to memorize the charges of some of the elements so that it will be easy. I hope this helps