How many atoms of phosphorus are in 8.10 mol of copper(ii) phosphate?

Similar to what 'Rosael' noted (thanks Rosael!) instead of just multiplying the 2 mols that Phosphorus has, in it's Cu3(PO4)2 compound... we need to recognize that the total amount of moles in 8.10 moles of the compound is actually (2 mols P x 8.10 mols of Cu3(PO4)3) from here we know that Cu3(PO4)2 contains 16.2 mols of P but because we are asked to figure out how many ATOMS 16.2 MOLS of P actually are... this is where we utilize Avagadro's wonderful # (i saw wonderful because it magically helps us switch back and forth from these sorts of things.)

We do this by saying:

16.2 mols of P x ( 6.022x10^23 atoms of P ) / 1 mol of P

writing this out will help you to see how the mols then cancel, and we end up only with atoms of P *Rember that Avagadro's # is there to help! It may not always go on top... sometimes you will need to divide by it to find how many mols is in something...* Hope this helped!

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6