Essay on Unit 5 Lecture 5

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UNIT 5 LECTURE 5
H Y B R I D O R B I TA L S

VALENCE – BOND THEORY
• While the discussions we have had about bonding has been correct, how can we explain this using quantum mechanics?
• Valence Bond Theory – Atoms bond when electron densities are concentrated between the two atoms nuclei. Bonding occurs when valence orbitals of each atom overlap.

QUICK WRITE
• Draw the Lewis structure for CF4. Predict the electron domain geometry and the molecular geometry of the compound.

CONSIDER CARBON…
• Carbon’s valence electron configuration looks like:

CONSIDER CARBON…
• If these form bonds with fluorine as predicted, then 3 of the bonds would have a higher energy than the 4th bond in the s orbital.
• The s and p orbitals “mix” in order to form new orbitals that have equal energy
• They form sp3 orbitals that allow for bonding to occur

CONSIDER CF4…

ORBITAL HYBRIDIZATION
• Hybrid Orbitals – The orbitals of an atom can “mix” to form new shapes
• These orbitals have a new energy level that is a mixture of the two old energy levels.
• Types formed…all depend on e- domains:






sp sp2 sp3 sp3d sp3d2

SP HYBRID ORBITALS
• Form when the central atom mixes 1 s and
1 p orbital to form 2 sp hybrid orbitals.
• Arranged in a linear shape and able to form
2 new bonds

SP2 HYBRID ORBITALS
• Occur when 2 p and 1 s orbital mix to form new shapes
• Hybrid orbitals arrange in a trigonal planar shape and 3 new bonds can form

SP3 HYBRID ORBITALS
• Occur when 3 p orbitals and 1 s orbital mix
• The 4 sp3 orbitals then arrange themselves such that a tetrahedral shape is formed.

MOLECULES WITH LONE PAIRS
• Central atoms often have lone pairs on them. • These electron pairs are put in their own hybrid orbitals.
• Example: H2O

QUICK WAY TO REMEMBER NUMBER OF
HYBRID ORBITALS

Number of Lone Pairs and/or Bonds for
Central Atom

Hybridization

2

sp

3

sp2

4

sp3

DSP3 AND D2SP3 HYBRIDIZATION
• For compounds with expanded Octets, d orbitals are hybridized. Number of Lone Pairs and/or Bonds for
Central Atom

Hybridization

5

dsp3

6

d2sp3

CLASS EXAMPLE
• Determine the orbital hybridization of the central atom for NH2 –

TABLE TALK
• Determine the orbital hybridization for SO32–

WHITE BOARD RACES

QUESTION 1
•…