[xiankai]

after finally getting into college, im getting pumped up learning new stuff, havent been around here alot. during a recent lecture about chemical bonding, i came across BeCl2, BCl3, PCl5, SF6, the examples illustrated in the lecture.

what was interesting is the way that the electrons were structured. BeCl2 lacks 4 e- for the Be atom, so it has 1s2 2s2 2p2 and BCl3 lacks 2 e- for the B atom and thus has 1s2 2s2 2p4. what makes these compounds stable? does their electron deficiency affect their stability in any way?

then about PCl5 and SF6. i learnt that the reason that they can possess more than 8 electrons due to the empty energetically accessible 3d subshell. but what is curious is the way the electrons are "restructured". for example

P in PCl5 = 1s2 2s2 2p6 3s2 3p3 --> 1s2 2s2 2p6 3s2 3p6 3d2

let us take into account the valence electrons only for convenience's sakes, where ( = left spin e-, ) = right spin e-

3s2 3p3 () ( ( (

becomes

3s1 3p3 3d1 ( ( ( ( (

and with shared electrons

3s2 3p6 3d2 () () () () ()

how does the e- from the 3s2 orbital jump up to the 3d1 orbital in the first place? surely such a drastic jump requires alot of energy...

[Mitch]

i learnt that the reason that they can possess more than 8 electrons due to the empty energetically accessible 3d subshell.

That is completely and totally wrong. Go to your professor and hit them on the back side of their head. Tell him you are a Chemist and you want to know the real Molecular Orbital Theory for what is going on. 3d Orbitals do not need to be invoked at all!

[Donaldson Tan]

hint: Be is in period 2. P is in period 3.

[billybo]

how about BeH3... Does that have any exceptions because it has too few electrons to bond to 3 Hs.