Three queries about expanded octets!

Question

∆ Why can some elements have expanded octets?? Is the only explanation that "the central atom uses its d orbital?"

 

∆ If yes, why can't any element use its "d" orbital when its in the center and thus have an expanded octet? 

 

∆ I even saw a Lewis structure with Xe having 14 electrons around it. What is the upper limit on what an atom can have around it in a Lewis structure?

 

 

I'd be really grateful to anyone who can help, this concept of expanded octets is really bugging me..😥

Answer 1

Don't let this concept "bug" you.  As with everything in the scientific world, there are exceptions to every rule.  I'll do my best to offer a plausible explanation, based on my somewhat limited knowledge of this exception to the octet "rule".

 

Metals like to donate electrons and so they tend not to have expanded octets even though they may have an empty d subshell.  Non-metals that have a d-subshell are capable of having expanded octets. If, for example, you consider Al, Si, P, S and Cl, they all can have expanded octets. .  You mention Xenon having 14 electrons and this can be true because Xe has an f subshell, and that has 7 orbitals. Since each orbital can hold 2 electrons, it can conceivably have 14 electrons.