Summer 2001 Notes June 13 June 15 June 18 June 20 July 2 Fall 2001 Lectures 9/28 10/1 10/3 10/5 – 10/8.
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Summer 2001 Notes
June 13 June 15 June 18 June 20 July 2
Fall 2001 Lectures
9/289/2810/110/310/5 – 10/8
2+
[Co(H2O)6]2+
Hydrolysis by complex ions
+ H2O(l)
+ H3O+
+ H2O(l)
+ H3O+
acidConjugatebase
Fe(H2O)63+(aq) + H2O(l)
H3O+(aq) + Fe(H2O)5OH2+(aq)
Fe(H2O)63+(aq) + H2O(l)
H3O+(aq) + Fe(H2O)5OH2+(aq)
Ka =[H3O+][Fe(H2O)5OH2+]
[Fe(H2O)63+]
= 7.7 x 10-3
Fe(H2O)63+(aq) + H2O(l)
H3O+(aq) + Fe(H2O)5OH2+(aq)
Ka =[H3O+][Fe(H2O)5OH2+]
[Fe(H2O)63+]
= 7.7 x 10-3
pH of 0.10 M Fe(H2O)63+
pH of 0.10 M Fe(H2O)63+
[Fe(H2O)63+] [H3O+] [Fe(H2O)5OH2+]
Startchangeequil.
0.10 0 0
pH of 0.10 M Fe(H2O)63+
[Fe(H2O)63+] [H3O+] [Fe(H2O)5OH2+]
Startchangeequil.
0.10 0 0
-x +x +x
pH of 0.10 M Fe(H2O)63+
[Fe(H2O)63+] [H3O+] [Fe(H2O)5OH2+]
Startchangeequil.
0.10 0 0
-x +x +x0.10 - x x x
pH of 0.10 M Fe(H2O)63+
[Fe(H2O)63+] [H3O+] [Fe(H2O)5OH2+]
Startchangeequil.
0.10 0 0
-x +x +x0.10 - x x x
Ka =(x)(x)
(0.10 - x)= 7.7 x 10-3
Ka =(x)(x)
(0.10 - x)= 7.7 x 10-3
pH of 0.10 M Fe(H2O)63+
Ka =(x)(x)
(0.10 - x)= 7.7 x 10-3
pH of 0.10 M Fe(H2O)63+
x2 = (7.7 x 10-3)(0.10 - x)
Ka =(x)(x)
(0.10 - x)= 7.7 x 10-3
pH of 0.10 M Fe(H2O)63+
x2 = (7.7 x 10-3)(0.10 - x)
x2 + (7.7 x 10-3)x - 7.7 x 10-4 = 0
Ka =(x)(x)
(0.10 - x)= 7.7 x 10-3
pH of 0.10 M Fe(H2O)63+
x2 = (7.7 x 10-3)(0.10 - x)
x2 + (7.7 x 10-3)x - 7.7 x 10-4 = 0
x = 0.024
Ka =(x)(x)
(0.10 - x)= 7.7 x 10-3
pH of 0.10 M Fe(H2O)63+
x2 = (7.7 x 10-3)(0.10 - x)
x2 + (7.7 x 10-3)x - 7.7 x 10-4 = 0
x = 0.024 pH = 1.6
Symmetry
Symmetry
Molecular symmetry
BF3
Symmetry
Molecular symmetry
BF3 BFF
F
Symmetry
Molecular symmetry
BF3 BFF
F
BFF
F
Symmetry
Molecular symmetry
BF3
BFF
F
Rotate 120o around an axis through B tothe plane of the screen.
Symmetry
Molecular symmetry
BF3
Rotate 120o
BFF
F
BFF
F
Symmetry
BF3
Rotate 120o
BFF
F
BFF
F
Since the fluorines are all identical,
we cannot tell the two molecules apart.
=
Symmetry
BFF
F
BFF
F
Since the fluorines are all identical,
we cannot tell the two molecules apart.
=
Rotate 120o Rotate 120o
Symmetry
BFF
F
Since the fluorines are all identical,
we cannot tell the two molecules apart.
=
Rotate 120o Rotate 120o
BFF
F
BFF
F
=
Symmetry
BF3
Rotate 120o
BFF
F
BFF
F
=
This is a 3-fold axis of symmetry.
A third 120o rotation brings themolecule back to the starting position.
Symmetry
BF3
BFF
F
Rotate 180o around the B - F axis.
Symmetry
BF3
Rotate 180o around the B - F axis.
BFF
F
BFF
F
Symmetry
BF3
Rotate 180o around the B - F axis.
BFF
F
BFF
F=
A second 180o rotation gives theoriginal molecule.
Symmetry
BF3
Rotate 180o around the B - F axis.
BFF
F
BFF
F
This is a 2-fold symmetry axis
=
Symmetry
BF3
BFF
F
BF3 has 3 2-fold symmetry axes.
Symmetry
BF3
BFF
F
B
F
mirror
Symmetry
BF3
BFF
F
B
F
Mirror plane of symmetry
BFF
F
=
Symmetry
BF3
BFF
F
B
F
BF3 has 3 mirror planes of symmetryalong the B-F bonds.
BFF
F
=
There is a mirror plane in the plane ofthe molecule.
BFF
F
1 3-fold axis normal to plane3 2-fold axes along B - F bonds3 mirror planes along bonds1 mirror plane in molecular plane
2+
2+
4-fold rotation axis
2+
4-fold rotation axis = 4 90o operations toget back to original configuration.
2+
4-fold rotation axis = 4 90o operations toget back to original configuration.
The octahedralcomplex willhave 3 4-foldaxes.
2+
Mirror planes?
2+
Mirror planes?
Co
OO
O O
2+
Mirror planes?
Co
OO
O O
3 mirror planes with Co and 4 H2O’s.
2+
Mirror planes?
Co
OO
O O
2+
Mirror planes?
Co
OO
O O
2+
Any otherrotation axes?
2+
Any otherrotation axes?
2+
Any otherrotation axes?
Octahedral complexes have 3-fold axes.
2+
Any othersymmetry elements?
2+
Any othersymmetry elements?
Inversion center
2+
Any othersymmetry elements?
Inversion centerThe Co is the inversion center.
2+
Any othersymmetry elements?
Inversion center
The Co is the inversion center. At any pointwhere there is a ligand, there is a ligand thesame distance in the opposite direction.
Tetrahedron
Tetrahedron
PerchlorateClO4
-
Tetrahedron PerchlorateClO4
-
1
2
3
4
1
2
3
4 =
2-fold
Tetrahedron PerchlorateClO4
-
1
2
3
4
1
2
3
4 =
Mirror plane
Tetrahedron PerchlorateClO4
-
1
2
3
41
2
3
4 =
3-fold axis Cl-O3
Tetrahedron PerchlorateClO4
-
1
2
3
4
4 3-fold rotations
3 2-fold rotations
3 mirror planes
+ others
octahemioctahedron
octahemioctahedron
4-fold rotation axes
octahemioctahedron
4-fold rotation axes
This is not a 3-fold
octahemioctahedron
4-fold rotation axes
This is not a 3-fold
octahemioctahedron
4-fold rotation axes
This is not a 3-fold
octahemioctahedron
4-fold rotation axes
This is not a 3-fold
a b The points a and b arerelated.
octahemioctahedron
4-fold rotation axes
ab
The combination of 120o
rotation and a mirrorleads to a new symmetryelement
octahemioctahedron
4-fold rotation axes
a b
The combination of 120o
rotation and a mirrorleads to a new symmetryElement - S3
Symmetry elements to look for-
rotations
mirrors
inversions
Crystals and solid-state structure
Crystals and solid-state structure
octahedron
Crystals and solid-state structure
Crystals and solid-state structure
Tetrahedralcoordination
Crystals and solid-state structure
Tetrahedralcoordination
C - C = 1.544 Å
Å = ångström = 10-10 m
Å = ångström = 10-10 m
The ångström is a useful unit when
describing bonding distances.
Symmetry of a tetrahedron
Tetrahedrons and cubes have 3-fold
axes of symmetry
Graphite Crystal
Graphite Structure
Graphite Structure
Hexagonal bondarray leads tohexagonal crystal
Graphite Structure
Bonds - strong attraction
Graphite Structure
Bonds - strong attraction
van der Waal’s forces- weak attraction
Hard structure - bondsare 3-dimensional
Soft structure - bonds are in twodimensions
Hard structure - bondsare 3-dimensional
Soft structure - bonds are in twodimensions
van der Waal’s forceseasy to break
BuckyBall a fullerene
C60
Individual moleculeof carbon atoms
OFB page 79crystals.
BuckyBall a fullerene
C60
NaCl
NaCl
SiO2
SiO2
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