Post on 31-May-2020
Welcome to 3.091Lecture 10
September 30, 2009
Hybridized & Molecular Orbitals; Paramagnetism
3.091 Test #1 Wednesday, October 7, 2009
Room Assignments
A – Ha: 10-250
He - Sm: 26-100
So - ∞: 4-270
Increasing
Electronegativity, χ
Incr
easi
ng
s Block p Block d Block f Block
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Image by MIT OpenCourseWare.
Group Classifications6
Atomic Number2
Oxidation States3
Symbol4
Electronic5
Configuration
Name4
bold indicatesmost stable state
Black = solid, red = gas,blue = liquid,outline = syntheticallyprepared
25
7VIIAVIIB
Mn
Atomic Weight1
Melting Point7, OC
Boiling Point7, OC
Density8, g/cm3
Electronegativity9
First lonizationPotential10, eV
(gases: g/L at 0OC, 1atm)
( ) Indicates most stableor best known isotope
54.93805
Manganese
124620617.471.55
7.435[Ar]3d54s2
2, 3, 4, 6, 7
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huh?
100
75
50
25
00.5 1.0 1.5 2.0 2.5 3.0 3.5
KF
CsF
LiFNaClKClCsCl
LiClCsIKBr
KI
LiI
HF
IFHCl
HBrIClHIIBr
LiBr
Perc
ent i
onic
cha
ract
er
Electronegativity difference
Huh?
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H 1s H 1s
H2
Electron-Pair Bond
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Ha
Hb
1sa
1sb
1sa
1sb
+ = MO I
Molecular Orbital _______ Bonding
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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.
E1s 1s
H (AO) H (AO)H2 (MOs)
σ1s
σ1s∗
+
+ -
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E1s 1s
He (AO) He (AO)He2 (MOs)
(c)
σ1s
σ1s∗
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E1s 1s
He (AO) He+ (AO)He2+ (MOs)
(b)
σ1s
σ1s∗
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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 Molecular orbital
_
X
Z
σnpz
Z
X
npz
Z
X
npz
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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.
2pxa2pxb
π2px
π2px* Antibonding
BondingLobes
Lobes
Nodal Plane
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X
Z +
npx
X
Z
npx
X
Z
πnpx
X
Z +
npy
X
Z
npy
X
Z
πnpy
Bonding
Atomic orbitals Molecular orbitals
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2p 2p
σ2p*
σ2p
σ2s*
σ2s
πx*
πx
πy*
πy
2s 2s
e.g. N2, B2, C2
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2p 2p
σ2p*
σ2s*
σ2s
σ2p
πx* πy*
2s 2s
6 bonding electrons
=> triple bond
N N946 kJ/mol
N2
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2p 2p
σ2p*
σ2s*
σ2s
σ2p
πx*
πx
πy*
πy
2s 2s
e.g. O2 & F2
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σ2p*
σ2p
πx*
πx
πy*
πy
σ2p*
σ2p
πx*
πx
πy*
πy
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2s-2pz interaction
Li2 Be2 B2 C2 N2 O2 F2
E
σ2pz∗
σ2s∗
σ2s
σ2pz
π2px,y∗
π2px,y
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2p 2p
σ2p*
σ2s*
σ2s
σ2p
πx* πy*
πx πy
2s 2s
6 bonding electrons2 anti bonding electrons
=> double bond
498 kJ/mol
O2
0 = 0
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2p 2p
σ2p*
σ2s*
σ2s
σ2p
πx* πy*
πx πy
2s 2s
6 bonding electrons4 anti bonding electrons
=> single bond
160 kJ/mol
F2
F-F
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Image by MIT OpenCourseWare.
paramagnetism in liquid oxygen
2p 2p
σ2p*
σ2s*
σ2s
σ2p
πx* πy*
πx πy
2s 2s
6 bonding electrons2 anti bonding electrons
=> double bond
498 kJ/mol
O2
0 = 0
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Averill, B., and P. Eldredge. Chemistry: Principles, Patterns, andApplications. Flat WorldKnowledge, 2011. ISBN: 9781453331224.
An sp2 Hybrid Orbital
Three sp2
Hybrid OrbitalsHybridization
2py
2px
2s
sp2
sp2
sp2 An sp2-Hybridized Atom
Side View
90o
p
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Sp2
Sp2Sp2 Z
P
Top View
C120o
120o
120o
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Sp2
Sp2 Sp2Sp2 Sp2
Sp2
Sp2
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Sp2
Sp2 Sp2
Sp2
Sp2
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Sp2
Sp2
Sp2
Sp2Sp2
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Image by MIT OpenCourseWare.
Figure 9.29
CCC CH
H
H
H
2pz 2pzH 1s
H 1s
H 1s
H 1s
sp2 sp2
z
(b) C2H4 pi bonding(a) C2H4 sigma-bonded framework
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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 !
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
105
104
103
102
10
105
104
103
102
10
1110 30 50 70 90
10 30 50 70 90
Cs Au
( Hoshino et al. 1975)
600oC
At % Au
σ o
hm-1
cm-1
Electronic conductivity
Ionic conductivityMolten salt
Liquid metal
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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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