why does phosphorus makes 5 bonds with oxygen in P4O10 whereas 3 bonds in P4O6?

how phosphorus forms 2 types of bonds with oxygen i.e. 5 in $\ce{P4O10}$ and 3 in $\ce{P4O6}$ when only three are needed to complete its octet?

• Did you consider the different oxidation states of phosphorus in both oxides? Apr 3 '15 at 10:22
• Welcome to chemistry.SE! I wouldn't rely too much on octet if I were you, especially when it's about phosphorus. Your question won't make sense if we not rely on octet, which is the case about group 15. Apr 3 '15 at 10:40
• @Ϻ.Λ.Ʀ. -- too bad there's no such simple reply for Cu(OH)2. I mean, as simple as Chinmay's. Jan 28 '16 at 17:54