[Herst]

Write the molecular equation for the reaction between Ni(ClO4)2 and KSCN.

because its a precipitation reaction, I would take the cation from the first reactant and put it with the second reactants anion, and vis/versa, right?

so it would be

Ni(ClO4)2(aq) + KSCN(aq) -> NiSCN(s) + K(ClO4)2(aq)

but apparently that isn't correct...

Ni and K are the cations, and (ClO4)2 and SCN are the anions, true?

can someone let me know what I'm doing incorrect please

[Borek]

I doubt in precipitation, more like complexation. But even assuming it is precipitation - do you know what valence/charge is? Do you know what anions/cations are present in your reactants? Do you know how to write dissociation reactions for your reactants?

[Herst]

I doubt in precipitation, more like complexation. But even assuming it is precipitation - do you know what valence/charge is? Do you know what anions/cations are present in your reactants? Do you know how to write dissociation reactions for your reactants?

I dont know what the valence charge is, I know the anions and cations, I listed them in the original post, were they not correct?
Is the valence charge the same as the oxidation number?

[Arkcon]

You performed a double replacement reaction, by swapping anions and cations.  However, the molecules in your products are not charge balanced, for one thing.  Also, once you form the correct products you will have to balance reactants and products.  Like Borek said, there is nothing in the question quoted that states conclusively that there is a precipitation.

[Borek]

I dont know what the valence charge is

You misunderstood me - there is no such thing as "valence charge", however, when predicting formulas of ionic substances you have to combine them in such a way that the resulting molecules are neutral; this is similar to combining atoms in such a way that all valences are used.

I know the anions and cations, I listed them in the original post, were they not correct?

You have not listed them correctly. Try again. SCN is not an anion - SCN^- is. Do the same with the remaining ones.