,Chapter 2 : Bonding in
Organic Molecules
1 Lewis
.
Bonding Model
octet
rule-every atom for chemical combination to acquire se around it
-
goes
Valence e- # bonds to
2nd now atom complete octet examples
-
(4)
C 4 - H
=
no lone
pairs
1 lone
-
(5) N 3 : NEN : pair
a
(6)
O 2
(7) F I H-F :
organic molecule example :
2 bromo 3 pentanone
HBTH "
COMPLETE LENIS STATE T
>
-
organic molecules are networks of C-c and C-It bonds
· use "line notation"
· assumed there are c-H bonds , but not explicitly written
, example 1 : 2 bromo spentanone
:
Bri ⑨
line representation of
molecule above
&
:
⑨
example 2
:H: ,
·
-
H o Ni
it it
line structure ONLY applies to C-H bonds,
other bonds should be written in Lewis format
11 . Formal charge
When
>
- atom forms lesser # of bonds than the ideal of bonds it formal
an or more , gets charge
, example 3 :
None
4e lone
H =
less
bondmeansextralonepaia
formed anEbonde As
I be N normally has one lone pair in ideal conditions
, ↳ example 4:
CH2N2
um
extra pair
Fl : 0 +o +
extend
O lone
- > Better option be minimizes charge
and allows octet rule (meaning possible
as many bonds as
· - =
F( : 0+ 1 -
2 = -
1 FC : -
1 + 1 -
1 = -
1
[CH30H27t * Skeletal structure : no lone pairs and
wun
end
i FC : 0 + 1 = + 1
/
REMEMBER Lewis
:
structure & FC should match the given Molecule (FC should be minimized to allow most bond formation
7
III Molecular Shape & Bond
.
Angle
-ond
I
of e- shape
groups Examples molecular angle
-
2
group 0 = c = 0 linear 1800
3
group
H trigonal planar 1200
4
group
I
i I
tetrahedral
I
109 50
.
I
↓ LONE PAIRS
-
lone pairs example Shape angle
I 1 lone
zione
pair
pair
H-
H
pyramidal
bent
<
109 50
109 50.
.
>
- non-stable molecules are called "intermediates"
↳ example : draw a 3-D structure of ICH3NHgJt , CHENHz , CHINH
H- Hig,
H
2
_
has to be 2D
Tetrahedralsaade
H -
H
c = N -
H
+
H
*+109
To
H
. 50 H
-109 50
N
E t H
.
·
H #109 30 .
+
109 50
.
, IV . & Molecular
Bond
Polarity Polarity
>
- Bond polarity
bonds shared
·
nonpolar : e-are equally between atoms w/ same
electronegativity
polar bonds : difference in between bonded
·
electronegativity atoms, OR
polarity is due to polarization of atoms
↳ polarizable atom-distribution of e- is
readily distorted due to
larger size
> Molecular
-
Geometry
·
dipole moment : Vector sum of individual dipole
Cl
↳ example :
*
different atoms =
unsymmetrical atom
*
be bond lengths would vary
C111/1 e)
Cl
⑭
Cl
NOTE : bond dipoles written as 'F from less electronegative tomore
are
goes a negative
↳ example :
16
St
8 -
St
N -
H
H
:
: H
- CS -
"T =nonpolar
↳ example :
-F BUT ,-
nonpolar POLAR
.
V Bonding in covalent molecules
I example/bondangee
I
_
hybrid. # Orbitals mol .
Shape
Sp 2 0 linear
Sp3
sp2
I
3
4
I
⑳ 1
1200
109 50 .
I
trigonal planar
tetrahedral
16 bonds are formed with hybridized orbitals and it bonds are formed W/ unhybridized p or d orbitals
F
S He
E Sp3
j :
10/sp3 be
4 orbitalon H66H
cyy
6
I
· So
F
be
F
3 eg
Try This :
H H
I ToA
3
it
ps 4 Spe
Organic Molecules
1 Lewis
.
Bonding Model
octet
rule-every atom for chemical combination to acquire se around it
-
goes
Valence e- # bonds to
2nd now atom complete octet examples
-
(4)
C 4 - H
=
no lone
pairs
1 lone
-
(5) N 3 : NEN : pair
a
(6)
O 2
(7) F I H-F :
organic molecule example :
2 bromo 3 pentanone
HBTH "
COMPLETE LENIS STATE T
>
-
organic molecules are networks of C-c and C-It bonds
· use "line notation"
· assumed there are c-H bonds , but not explicitly written
, example 1 : 2 bromo spentanone
:
Bri ⑨
line representation of
molecule above
&
:
⑨
example 2
:H: ,
·
-
H o Ni
it it
line structure ONLY applies to C-H bonds,
other bonds should be written in Lewis format
11 . Formal charge
When
>
- atom forms lesser # of bonds than the ideal of bonds it formal
an or more , gets charge
, example 3 :
None
4e lone
H =
less
bondmeansextralonepaia
formed anEbonde As
I be N normally has one lone pair in ideal conditions
, ↳ example 4:
CH2N2
um
extra pair
Fl : 0 +o +
extend
O lone
- > Better option be minimizes charge
and allows octet rule (meaning possible
as many bonds as
· - =
F( : 0+ 1 -
2 = -
1 FC : -
1 + 1 -
1 = -
1
[CH30H27t * Skeletal structure : no lone pairs and
wun
end
i FC : 0 + 1 = + 1
/
REMEMBER Lewis
:
structure & FC should match the given Molecule (FC should be minimized to allow most bond formation
7
III Molecular Shape & Bond
.
Angle
-ond
I
of e- shape
groups Examples molecular angle
-
2
group 0 = c = 0 linear 1800
3
group
H trigonal planar 1200
4
group
I
i I
tetrahedral
I
109 50
.
I
↓ LONE PAIRS
-
lone pairs example Shape angle
I 1 lone
zione
pair
pair
H-
H
pyramidal
bent
<
109 50
109 50.
.
>
- non-stable molecules are called "intermediates"
↳ example : draw a 3-D structure of ICH3NHgJt , CHENHz , CHINH
H- Hig,
H
2
_
has to be 2D
Tetrahedralsaade
H -
H
c = N -
H
+
H
*+109
To
H
. 50 H
-109 50
N
E t H
.
·
H #109 30 .
+
109 50
.
, IV . & Molecular
Bond
Polarity Polarity
>
- Bond polarity
bonds shared
·
nonpolar : e-are equally between atoms w/ same
electronegativity
polar bonds : difference in between bonded
·
electronegativity atoms, OR
polarity is due to polarization of atoms
↳ polarizable atom-distribution of e- is
readily distorted due to
larger size
> Molecular
-
Geometry
·
dipole moment : Vector sum of individual dipole
Cl
↳ example :
*
different atoms =
unsymmetrical atom
*
be bond lengths would vary
C111/1 e)
Cl
⑭
Cl
NOTE : bond dipoles written as 'F from less electronegative tomore
are
goes a negative
↳ example :
16
St
8 -
St
N -
H
H
:
: H
- CS -
"T =nonpolar
↳ example :
-F BUT ,-
nonpolar POLAR
.
V Bonding in covalent molecules
I example/bondangee
I
_
hybrid. # Orbitals mol .
Shape
Sp 2 0 linear
Sp3
sp2
I
3
4
I
⑳ 1
1200
109 50 .
I
trigonal planar
tetrahedral
16 bonds are formed with hybridized orbitals and it bonds are formed W/ unhybridized p or d orbitals
F
S He
E Sp3
j :
10/sp3 be
4 orbitalon H66H
cyy
6
I
· So
F
be
F
3 eg
Try This :
H H
I ToA
3
it
ps 4 Spe
