Pertemuan 1Pertemuan 1Jan 9, 2016

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H. H.

H. H.

H H

IKATAN KOVALENIKATAN KOVALEN

Tumpang tindih orbital

Pembentukan Ikatan

Atom yang terpisah

atomsmovecloser

( Model tumpang tindih orbital)

OrbitalsOrbitals

The region of space around an atom in which an electron is likely to be found is an orbital.

The shape and size of the orbital are determined by a mathematical equation called a wave function.

OrbitalsOrbitals

When atoms combine to form molecules, they do so by combining the wave functions for the individual atomic orbitals.

We say that the orbitals “overlap.”The region of space defined by this

combination of orbitals is the molecular orbital.

Sigma BondsSigma BondsHead-on overlap of atomic

orbitalsElectron density is a symmetrical

cylinder around the bond axisAtomic orbital combinations that

give bonds:s s p p ps

Pi BondsPi BondsSide-on overlap of atomic orbitalsElectron density is above and below a

nodal plane on the internuclear axisAtomic orbital combinations that give

bonds:p p p d

HYBRIDIZATIONHYBRIDIZATION

HOW ARE THE OBSERVED BOND ANGLES ACHIEVED?

“Vision is the art of seeing things invisible.”Jonathan Swift

Xunhybridized atom

2s

2pz

2py

2px

2s

2pFORMATION OFFORMATION OFSPSP33 HYBRID ORBITALS HYBRID ORBITALS

Xsp3 hybridized atom

(1) (2) (3) (4)

FORMATION OFFORMATION OFSPSP33 HYBRID ORBITALS HYBRID ORBITALS

These orbital shapes arecartoons - actual shapesare shown on the nextslide. [animation]

Ikatan padaIkatan pada

Alkana sp3

Alkena sp2

Alkuna sp

C

Carbon has 4 valence electrons, 2s22p2

.. .

.

Carbon can form single, double or triple bonds

sp, sp2 and sp3 hybrid orbitals.

Let’s do sp3 first.

2p

2s

hybridize sp3

ALKANA

H

H

H

H

CC H

H

HH

H

H

C CH H

H

H H

H

POSTEST

Buatlah hibridisasi etana(Selengkaplengkapnya menurut pemahaman anda)Ditulis dalam kertasNama:NIM:

TUGAS KELOMPOKMenulis Hibridisasi yang mengandung unsur:

1.Kelompok 1 absen 1-6 unsur N2.Kelompok 2 absen 7-12 unsur O3.Kelompok 3 absen 8-18 unsur P4.Kelompok 4 absen 19-24 unsur Cl5.Kelompok 5 absen 25-32 unsur B6.Kelompok 6 absen 33-41 unsur F

Multiple Bonds and hybridization

Ethylene C CH

H

H

H

Each carbon is hybridized sp2 . The hydrogens are 1s. One of the double bonds is sp2 - sp2. The other one isp - p.

2p

2s

hybridize

2p

sp2

ALKENA

C C

Note that a double bond consists of a and a type bond

C CH

H

H

H

C CH

H

H

H

What about acetylene?

C CH HEach carbon atom is sp hybridized. The hydrogens areunhybridized, 1s orbitals.

2p

2s

hybridize

2p

sp

Note that a triple bond consists of a and 2 bonds. Thetwo bonds use unhybridized p orbitals.

ALKUNA

CCH H

C C HH

C

H

H HH

:

: ....

symmetrical moleculeall repulsions are equal

perfect tetrahedralall angles 109o28’

NH H: ....H

.. anglebecomeslarger

larger repulsion

repulsionsmaller angle becomes

smaller

not all pairs are equivalent

the unshared pairs repel morestrongly than the bonded pairs

Electron Pair RepulsionElectron Pair Repulsion

Effect of double bond and electronegativity

C CHH

H H

C OH

H

C CH2

H

H

C CH2

Cl

Cl

C CH2

F

FC O

F

F

C OCl

Cl

C OH

H117o

121.5o

121.5o

123o

125o

117o

114o

110o

116o

122o

116o

124.5o

126o

111o

108o

122o

OC

H

H

H

H

2s2p

sp3 hybrids

hybridization C OHH

H

Hsp3 sp3 Metanol

2s2p

sp2

hybridization

2p

2p

C OH

HC

HO

H

used forbond

used forbonds

sp2

sp2

C CCH

H

H

H

C C CH

H

H

Hallena

sp2sp2sp

CH

HH H

endview

molecule has a twist in the center

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