1Hybridization

HybridizationHow atomic orbitals form other orbitals that are directional

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2

Hybridization

The shapes of the atomic orbitals are inappropriatefor the formation of bonds within the molecules. For example, here are the shapes of the s and patomic orbitals:

X

Y

Z

pzs px py

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Hybridization

To share electrons, the electron wave needs to bein the direction of the atom be bonded. The sorbital is not directional and the p orbitals aredirected along the x, y and z axises, but equally inboth positive and negative directions.

X

Y

Z

pzs px py

4

Hybridization

To solve this problem, recall that these are waves. As such one can recombine them in such a way asto form new waves that, although look different, areoverall identical. Here are the ways that they arecombined.

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Hybridization

The first combination is to combine the s orbital withone of the p orbitals. These are referred to as sphybrids. There are 2 to start with and 2 resultant.

– ½ !½

!+ ½ ½

Red here indicates a “trouth” in the wave functionand Green represents a “peak”.

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Hybridization

The first combination is to combine the s orbital withone of the p orbitals. These are referred to as sphybrids. There are 2 to start with and 2 resultant.

The small “trouth” in the hybrids are usually notshown in the overall picture since they are notinvolved in the final bonding. The two togetherlooks like this:

X

Along one of the axes.

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Hybridization

More complicated is the sp2 hybrid formed from an sorbital 2 of the p orbitals. There are 3 to startingorbitals and 3 resulting hybrid orbitals.

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Hybridization

The sp2 hybrid formations:

– ½ !

!½

– ¼

!+ ½

¼

+ ½

– ¼¼

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Hybridization

...or more simply for the sp2 hybrid formations:

!+

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Hybridization

The next more complicated combination is thecombination the s orbital with three of the p orbitals. These are referred to as sp3 hybrids. There are 4 tostart with and 4 resulting orbitals.

These are shown on the next slide.

11

Y

Hybridization

Combinating 1 s orbitalwith 3 p orbitals yield 4 sp3

hybrids.

X

! Z

X

Y

+

Z Z

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Hybridization

or, showing sp3 hybrid formations altogether:

Y

X

Y

+

Z

ZX!

13

X

Hybridization

So far these are the hybrids allowed for the rule of8. The geometry of these are:

X

Y

ZX

sp3 - tetrahedralsp - linear sp2 - trigonal

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Hybridization

There are 2 more hybrids which use the d orbitals. These hybrids are for those central atoms whichhave 10 or 12 electrons about them.

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Hybridization

For those central atoms which have 10 electronsabout them, a hybrid is formed from an s, 3 ps and1 d orbital to for 5 sp3d hybrids.

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Hybridization

For those central atoms which have 10 electronsabout them, a hybrid is formed from an s, 3 ps and1 d orbital to for 5 sp3d hybrids. These look like:

Z

Y

X

17

X

Z

Y

Hybridization

This is a trigonal bipyramid. One can envision thisas two orbitals on the y-axis, up and down, andthree around the waist at 120E from each other:

back

to the side

forward

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Hybridization

For those central atoms which have 12 electronsabout them, a hybrid is formed from an s, 3 ps and2 d orbital to for 6 sp3d2 hybrids.

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Hybridization

For those central atoms which have 12 electronsabout them, a hybrid is formed from an s, 3 ps and2 d orbital to for 6 sp3d2 hybrids. This looks like:

X

Z

Y

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Hybridization

This is the octahedral arrangement with 2 orbital oneach of the axis in the + and – direction:

X

Z

Y

Hybridization

X

Z

Y

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Hybridization

Hybrids are formed from the following atomicorbitals, yielding the following shapes for the orbitalsformed:

1 s and 1 p - 2 sp hybrids - linear 1 s and 2 ps - 3 sp2 hybrids - trigonal1 s and 3 ps - 4 sp3 hybrids - tetrahedral1 s, 3 ps and 1 d - 5 sp3d hybrids - trigonal bipyramid1 s, 3 ps and 2 ds- 6 sp3d2 hybrids - octahedral

22The End of Hybridization Follow this up with the 2nd slideshow on hybridization

The End of HybridizationFollow this up with the 2nd slideshow on

hybridization

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