What’s the the ionic formula that could be derived from the given item in the chart.

So to complete this chart, we have to remember that compounds want to retain a neutral charge. Therefore, we need to compensate a difference in charge by adding more of that element in the compound.

So let's take and . Since cyanide has a -1 charge and gold has a +3 charge, we are going to need 3 moles of cyanide per mole of gold. So then the neutral compound of gold cyanide would be:

Then we have and . In order to compensate for the +1 charge on the potassium being one less than the carbonate's -2 charge, we are going to need two moles of potassium for every carbonate. So then the compound will be:

And lastly we have and . Since these charges don't balance easily, we can then find the lowest common multiple - in this case it will be 6. So to get a +6 charge, we will need 2 moles of gold, and to get a -6 charge, we will need 3 moles of carbonate. Then we put it into the compound formula: