Hybridization:TheShapeOfThingsToComeA. Intro

B. Electron Counting InAtoms

neon potassium silicon

1s2 1s22s22p63s23p6 1s22s22p62s22p6 4s1 3s23p2[Ar] or

nitrogen carbon hydrogen

1s2 2s2 2p3 1s2 2s2 2p2 1s1

fluorine bromine chlorine

1s2 2s2 2p5 [Ar] 3d10 4s24p5 1s2 2s2 2p6 3s2 3p5

oxygen sulfur boron

1s2 2s2 2p4 1s2 2s2 2p6 3s2 3p4 1s2 2s2 2p1

InMolecules,andValency 2 electrons in the first shell, 8 in the second, 16 in the third. share completely donate or receive electrons. each hydrogen atom has 2 first shell electrons One bond containing 2 electrons is formed in this sharing process valency of hydrogen in H2 is 1 He C ___4____ N ___3____ O ____2___ F ___1____ Cl ___1____ Br ___1____ S ___2____ may only bring 1 common molecules is 1. C ___CH4__ N __NH3___ O __H2O___ F __HF____ Cl ___HCl___ Br __HBr____ S __H2S___

N 2s22p12p12p11s11s11s1 H3

The blue and red electrons are shared in bonds, two per bond, so ammonia has two electrons that are not in bonds, ie a lone pair.

H2 1s11s12p12p12p12p12s2 O 2 2 H 1s12p12p12p12p12p12s2 F 1 3

1 3 H 1s14p14p14p14p14p13d104s2 Br C 2s22p12p11s11s11s11s1 H4 4 0

favored electron count for that is 8 B 2s22p11s11s11s1 H3 3 0 H2 1s11s13p13p13p13p13s2 S 2 2

Si 3s23p13p11s11s11s11s1 H4 4 0 P 3s23p13p13p11s11s11s1 H3 3 1

electrons is lost

C. Mixing Atomic Orbitals To Maximize Overlap In Molecules Combinings-andp-Orbitalscalled atomic orbitals. have different shapes as atomic orbitals.

waterelectronic structure

bonds lone pairs hydrogen fluorideelectronic structure

bonds lone pairs

hydrogen bromideelectronic structure

bonds lone pairs methaneelectronic structure

bonds lone pairs

boraneelectronic structure

bonds lone pairs hydrogen sulfideelectronic structure

bonds lone pairs

tetrahydrosilaneelectronic structure

bonds lone pairs phosphineelectronic structure

bonds lone pairs

hybridized to make them. 2 molecular orbitals, of three gives 3, and of n gives n. denoted as sp, whereas sp2 surfaces are formed if two p-orbitals are mixed with one s-. a ___sp3 __ hybrid. GeometricShapes

the boy in the middle. girl-boy-girl angle is 180 ideal bond angle. middle of a triangle with then 120°. a tetrahedron, 109°.

s- d- d- p-

straight line connecting three dots a triangle a square

a tetrahedron a trigonal bipyramid an octahedron

ShapesOfMoleculesBasedOnGeometricShapes2 sp-hybrid orbitals. 3 hybrid orbitals, and 4 arise from. Bold lines mean dashed lines

will be sp2 hybridized. A tetrahedron of sp3 hybrids if 4 bonds sp hybrid orbitals. 0 lone pairs it is tetrahedral. 3 lone pairs. 4 entities hydrogen fluoride is approximately tetrahedral. Water 4 objects tetrahedral hydrogen chloride, 4 Cl is tetrahedral

sp3 sp2 sp

ammonia, 4 tetrahedral hydrogen sulfide, 4 tetrahedral arrangement; and, borane, 3 triangular arrangement. C in methane is tetrahedral with a dihedral angle of 109° O in water is tetrahedral with a dihedral angle of 109° Br in hydrogen bromide is tetrahedral with a dihedral angle of 109° N in ammonia is tetrahedral with a dihedral angle of 109° S in H2S is tetrahedral with a dihedral angle of 109° B in BH3 is trigonal with a dihedral angle of 120°

an sp hybrid consisting of 2 MOs in a linear arrangement with a dihedral angle of 180°

3 sp2 MOs, and these arrange in a trigonal arrangement with a dihedral angle of 120°

4 sp3 MOs, and these arrange in a tetrahedral arrangement with a dihedral angle of 109°

sp sp2 sp3

HC

H

H H

water hydrogen fluoride methane

HO

Heg

HF

hydrogen sulfideHBr BH3

HBr B

HS

H

PH3 SiH4 CCl4

HP

H

H

HSi

H

H H

ClC

Cl

Cl Cl

D. Multiple Bonds 8 electrons in its second shell 7 electrons in its second shell; this is not a are relatively reactive. sp3 hybridized

H

CH

H sp3 sp2

CHH

H

s-bonded sp hybridized C-atoms

are called sigma. pi bond. Maximal overlap is achieved Perpendicular p-orbitals do interact. of a p bond. 1 line(s), and p-bonds are represented by adding 2 parallel line(s).

because they would not contribute to the binding interaction. Atoms in molecules can selectively

CC

ethene before mixing p-orbitals

CC

ethene after mixing p-orbitals

OO

OH

NH O

OH

OH

# __2__isoprene

# __2__pyruvic acid

# __1__an imine

# __1__lactic acid

# _3___benzene

# __1__β-pinene

Carbene, CH2, 6 shared electrons in the C-second shell. this is called the singlet state. Alternatively, carbenes can be sp2-hybridized with one electron in each of the hybrid lobes that does not point to a hydrogen; this is a triplet state.

s-bonded sp hybridized C-atoms

H

CH

triplet

CH H C

unstable triplet singlet

CH

ethyne before mixing p-orbitals

C H CH

ethyne after mixing p-orbitals

C H

two p bonds surrounding the s bond called a triple bond.

it does not matter if. are sp hybridized, three sp2, and four sp3.

# __1__propyne

# __1__1-butyne

# __1__2-butyne

# __0__butane

# __1__acetonitrile

# __2__1,3-butadiyne

N

propane hexane methylcyclohexane

H3C

H2C

CH3 H3C

H2C

CH2

H2C

CH2

CH3

H2CH2C C

H2

CH2

CH2sp3 sp3

sp3

CHCH3 sp3

sp3

acetone 1-pentene 1-methylcyclohexene

H3CC

CH3 H3C

H2C

CH

HC

CH2

CH3

H2CH2C C

H2

CH2

CHsp2 sp2

sp3

CCH3 sp2

sp3

O

sp2 sp2

acetic acid cis-1-hydroxy-2-butene

H3CC

CH3 HO

H2C

CH

HC

CH2

CH3

H2CH2C S

CH2

CHCOH

Osp2sp2

sp2sp2sp2 sp3

sp3

sp3

H3CC

CH2

H2C

CH2

H2C

CH3

O HCHC

CH

CHC

HC Cl

H3C C C CH2H2C OH

sp3sp2sp2

sp3

sp2

sp

sp3

OCH3CHCCH3

CHC

HC C

HC C O CH3CHC

HCC

H

naproxen

OHCP

OHHO

O

P OHOH

O

H2C CH2

H2C NH2

alendronate

O OH

CHCHC

HC CHC O CH3

O

aspirin

sp2sp3

sp2

sp3

sp3

sp3

sp3sp2 sp3

sp3

sp3

CH3CC

HNH

CH2CH

CNN+

-NCHCH2HO

O

OHN O

zidovudine (AZT)

sp2

spsp2