Welcome to 3.091
Lecture 10
September 30, 2009
Hybridized & Molecular Orbitals; Paramagnetism
3.091 Test #1
Wednesday, October 7, 2009
Room Assignments
A – Ha:
He - Sm:
So - ∞:
10-250
26-100
4-270
Increasing
Increasing
Electronegativity, χ
s Block
p Block
d Block
f Block
Image by MIT OpenCourseWare.
Image by MIT OpenCourseWare.
Atomic Number2
Oxidation States3
bold indicates
most stable state
Symbol4
Black = solid, red = gas,
blue = liquid,
outline = synthetically
prepared
Electronic5
Configuration
Atomic Weight1
7
VIIA
VIIB
Group Classifications6
25
2, 3, 4, 6, 7
Mn
( ) Indicates most stable
or best known isotope
54.93805
1246
2061
7.47
1.55
7.435
[Ar]3d54s2
Manganese
Melting Point7, OC
Boiling Point7, OC
Density8, g/cm3
(gases: g/L at 0OC, 1atm)
Electronegativity9
First lonization
Potential10, eV
Name4
Image by MIT OpenCourseWare.
Percent ionic character
100
75
KI
KBr
CsI
NaCl
LiCl
LiBr
LiI
LiF
KCl
CsCl
KF
CsF
Huh?
huh?
50
HF
25
HCl
0
IBr
ICl
HI
0.5
IF
HBr
1.0
1.5
2.0
2.5
3.0
3.5
Electronegativity difference
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Electron-Pair Bond
H
1s
H
1s
H2
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1sa
Ha
1sa
+
1sb
Hb
=
MO I
1sb
Molecular Orbital _______ Bonding
Image by MIT OpenCourseWare.
Image by MIT OpenCourseWare.
Copyright © 2003 John Wiley & Sons, Inc.
Reprinted with permission of John Wiley
& Sons., Inc.
Source: Spencer, J. N., G. M.
Bodner, and L. H. Rickard. Chemistry:
Structure and Dynamics. 2nd edition.
New York, NY: John Wiley & Sons, 2003.
H2 (MOs)
H (AO)
H (AO)
-
+
∗
σ1s
E
1s
1s
σ1s
+
Image by MIT OpenCourseWare.
(c)
He (AO)
He2 (MOs)
He (AO)
∗
σ1s
E
1s
1s
σ1s
Image by MIT OpenCourseWare.
(b)
He (AO)
He2+ (MOs)
He+ (AO)
∗
σ1s
E
1s
1s
σ1s
Image by MIT OpenCourseWare.
Image by MIT OpenCourseWare.
Copyright © 2003 John Wiley & Sons, Inc.
Reprinted with permission of John Wiley & Sons., Inc. Source: Spencer, J. N., G. M. Bodner, and
L. H. Rickard. Chemistry: Structure and Dynamics. 2nd edition. New York, NY: John Wiley & Sons, 2003.
Bonding
Atomic orbitals
X
X
X
Z
npz
Molecular orbital
_
Z
Z
npz
σnpz
Image by MIT OpenCourseWare.
Copyright © 2003 John Wiley & Sons, Inc.
Reprinted with permission of John Wiley & Sons., Inc. Source: Spencer, J. N., G. M. Bodner, and
L. H. Rickard. Chemistry: Structure and Dynamics. 2nd edition. New York, NY: John Wiley & Sons, 2003.
2pxb
2pxa
Lobes
*
π2p
x
π2px
Antibonding
Nodal Plane
Bonding
Lobes
Image by MIT OpenCourseWare.
Bonding
Atomic orbitals
X
Molecular orbitals
X
Z
+
X
Z
Z
npx
npx
πnpx
X
X
X
Z
npy
+
Z
npy
Z
πnpy
Image by MIT OpenCourseWare.
σ2p*
πx*
πy*
2p
2p
σ2p
πy
πx
σ2s*
2s
2s
σ2s
e.g. N2, B2, C2
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N2
σ2p*
πx*
6 bonding electrons
=> triple bond
N N
946 kJ/mol
πy*
2p
2p
σ2p
σ2s*
2s
2s
σ2s
Image by MIT OpenCourseWare.
σ2p*
πx*
πy*
2p
2p
πx
πy
σ2p
σ2s*
2s
2s
σ2s
e.g. O2 & F2
Image by MIT OpenCourseWare.
σ2p*
πx*
σ2p*
πy*
σ2p
πx
πy
πx*
πy*
πx
πy
σ2p
Image by MIT OpenCourseWare.
2s-2pz interaction
∗
σ2p
z
∗
π2p
x,y
E
π2p
x,y
σ2p
z
∗
σ2s
σ2s
Li2
Be2
B2
C2
N2
O2
F2
Image by MIT OpenCourseWare.
6 bonding electrons
2 anti bonding electrons
=> double bond
O2
σ2p*
πx*
0=0
498 kJ/mol
πy*
2p
2p
πx
πy
σ2p
σ2s*
2s
2s
σ2s
Image by MIT OpenCourseWare.
6 bonding electrons
4 anti bonding electrons
=> single bond
F2
σ2p*
πx*
F-F
160 kJ/mol
πy*
2p
2p
πx
πy
σ2p
σ2s*
2s
2s
σ2s
Image by MIT OpenCourseWare.
Image by MIT OpenCourseWare.
6 bonding electrons
2 anti bonding electrons
=> double bond
O2
σ2p*
πx*
0=0
498 kJ/mol
πy*
2p
2p
πx
πy
σ2p
σ2s*
2s
2s
σ2s
Image by MIT OpenCourseWare.
paramagnetism in liquid oxygen
Averill, B., and P. Eldredge. Chemistry: Principles, Patterns, and
Applications. Flat WorldKnowledge, 2011. ISBN: 9781453331224.
2py
Three sp2
Hybrid Orbitals
Hybridization
2s
An sp2
Hybrid Orbital
2px
p
90o
sp2
sp2 An sp2-Hybridized Atom
sp2
Side View
Image by MIT OpenCourseWare.
P
Sp2
Sp2
Sp2
Z
Top View
120o
120o
C
120o
Image by MIT OpenCourseWare.
Sp2
Sp2
Sp2
Sp2
Sp2
Sp22
Image by MIT OpenCourseWare.
Sp2
Sp2
Sp2
Sp22
Image by MIT OpenCourseWare.
Sp2
Sp2
Sp2
Sp2
Sp2
Image by MIT OpenCourseWare.
Image by MIT OpenCourseWare.
Figure 9.29
(a) C2H4 sigma-bonded framework
H 1s
H 1s
sp2 C
H 1s
(b) C2H4 pi bonding
z
H
C sp2
H
2pz
2pz
C
C
H
H
H 1s
Image by MIT OpenCourseWare.
Extremes in electronegativity
NaI: Δχ = 1.73
CsAu: Δχ = 1.75
Cs and Au, both metals, melt to form metallic liquids, but…
when the concentration nears 50% (equal numbers of donors & acceptors)
 electron transfer occurs  !
metallic melt turns into molten salt!!
 clear, colorless liquid
 big drop in electrical conductivity
 shift from electronic to ionic conduction
 cesium auride
Extremes in electronegativity
NaI: Δχ = 1.73
CsAu: Δχ = 1.75
Cs and Au, both metals, melt to form metallic liquids, but…
when the concentration nears 50% (equal numbers of donors & acceptors)
 electron transfer occurs  !
metallic melt turns into molten salt!!
 clear, colorless liquid
 big drop in electrical conductivity
 shift from electronic to ionic conduction
 cesium auride
Specific electrical conductivity of liquid Cs _ Au alloys as a function of concentration
( Hoshino et al. 1975)
105
10
30
σ ohm-1 cm-1
Liquid metal
50
70
90
10
5
Electronic conductivity
600oC
104
104
103
103
2
10
2
10
10
10
Molten salt
Ionic conductivity
1
Cs 10
30
50
70
1
90 Au
At % Au
Image by MIT OpenCourseWare.
Extremes in electronegativity
NaI: Δχ = 1.73
CsAu: Δχ = 1.75
Cs and Au, both metals, melt to form metallic liquids, but…
when the concentration nears 50% (equal numbers of donors & acceptors)
 electron transfer occurs  !
metallic melt turns into molten salt!!
 clear, colorless liquid
 big drop in electrical conductivity
 shift from electronic to ionic conduction
 cesium auride
Extremes in electronegativity
NaI: Δχ = 1.73
CsAu: Δχ = 1.75
Cs and Au, both metals, melt to form metallic liquids, but…
when the concentration nears 50% (equal numbers of donors & acceptors)
 electron transfer occurs  !
metallic melt turns into molten salt!!
 clear, colorless liquid
 big drop in electrical conductivity
 shift from electronic to ionic conduction
 cesium auride
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3.091SC Introduction to Solid State Chemistry
Fall 2009
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