Understanding the Octet Rule and Electron Configuration in Compounds

[Chumchum]

Hi I'm unsure about how I can tell whether or not a compound has too many electrons, too few electrons, has an odd number of electrons, or follows the octet rule. I know B and Be are exceptions, but what about compounds that have Xe and S such as XeF4 and SO2?

 

[Plastic Photon]

don't think about electrons in general, be more specific and think valence electrons

 

[Harmony]

For those elements belongs to period 1 and 2, such as N, the elements have only two orbitals, hence the maximum number of electron accommodated by the elements are only 8 electrons, not more than that. These elements will generally follow the octet rules.

However, for elements that have more than 2 orbitals, they may (not necessarily)expand their valency to the d orbital, which means they can accommodate more than 8 electrons. Eg. PCl5 If you found that the central atom accommodate more than 8 valence electron, then the compound doesn't follow the octet rule, and has too many electrons.

XeF4 certainly has more than 8 valence electron, as there are 12 electrons. (Xe shares 4 electron pair with 4F)