how do i know what the ions present are of this formula:

Na3PO4

what are the anions and what are the cations? how do you know

C'mon you guys.

Na3PO4 ==> 3Na^+ + PO4^-3
The cation is Na^+ (it has a charge of +1) and there are three of them. The anion is phosphate, PO4^-3 and it has a charge of -3.
What do noble gases have to do with ions. The simple ones, such as Na^+, are isoelectronic with the nearest noble gas.

it is based on the placement of the element on the periodic table

can you explain more? i put the cation was Na3+ and the anion was PO4-. but it said it was wrong. what am i doing wrong?

Na is +1 and is the cation and PO4- is a polyatomic ion and the anion the placement always goes to your noble gases in column VIIIA (18)

I put Na+ as the cation and it counted it wrong. also. are you saying PO4- is the anion? cause i got it wrong.

and what do the noble gases have to do with the ions.

sorry im asking many questions

total you have 3 Na ions and 1 PO4- ions...so all together 4 ions

it says those answers are wrong

I don't know then...unless it is separating out each element...then it will have Na=3 P=1 and O=4...then it would be your 3 anions and 5 cations

this is what it says:

For the soluble compounds, write the ions present in solution.

this is the soluble compound:
Na3PO4

then it has 2 boxes one called cations and one called anions

thanks sooo much!!