Please help me understand hybridization, orbitals...

[Aletheia]

I am thoroughly confused with this topic after having studied it many times. I don't understand how, when given a structure (say CH4), you know what S orbitals and what P orbitals, etc, come together and how many times they come together to create sp, sp2, etc... If anyone can explain this to me, that would be fantastic. Thanks!

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[PiBond]

I am thoroughly confused with this topic after having studied it many times. I don't understand how, when given a structure (say CH4), you know what S orbitals and what P orbitals, etc, come together and how many times they come together to create sp, sp2, etc... If anyone can explain this to me, that would be fantastic. Thanks!

to determine hybridization of an atom, count the number of bonds and lone pairs at the central atom. Double and triple bonds count as one bond. For CH4, there's four bonds to carbon so the hybridization is sp3.

For a carbonyl compound, the carbonyl compound would be sp2.

Sp hybridization is seen when carbon (or nitrogen) has three bonds to it.

There's one exception to the hybridization rules that occurs when an atom with a lone pair is adjacent to an sp2 hybridized atom. In this case, the adjacent atom is also sp2 hybridized due to resonance (note: atoms hybridize at the most stable state and sp2 is preferred to sp3). We see this mostly with amide bonds--this is the reason peptide bonds are stable and exhibit planarity and the inability to rotate.

 

[Isoprop]

look at the geometry of the atom:

linear = sp
trigonal planar = sp2
tetrah = sp3
trig bipyramidal = dsp3
octehedral = d2sp3

example 1: the oxygen atom in water has a tetrahedral geometry so it is sp3
example 2: XeF4 has a octehedral geometry around the Xe atom. so that atom has d2sp3 hybridization.

there are some exceptions like the above poster mentioned.

 

[Aletheia]

Okay. Thanks. Are there exceptions to Benzene rings?

 

[PiBond]

Okay. Thanks. Are there exceptions to Benzene rings?

not that I'm aware of. if there are it's beyond the scope of the mcat