Transcript Slide 1
“Advanced General Chemistry”
Chemistry 201
Prof. Gordie Miller
Websites: Teaching Assistants:
http://avogadro.chem.iastate.edu/chem201/ WebCT:
https://webct.its.iastate.edu/ Daping Jing (Sect. 5 & 6; Chem 201L: Sect. 3 & 5) Philip Carlson (Sect. 4; Chem 201L: Sect. 4 & 6)
Sect. 4
in 1801 Gilman;
Sect. 5 & 6
in 1114 Gilman Wednesdays: Exam Dates: Final: Resources:
E-Resources for Chemistry
(Library Website)
Handbook of Chemistry & Physics
(CRC Handbook)
Please show respect to your colleagues:
Turn off cell phones, put aside the
Daily
, do not use iPods, laptops, or other devices for messaging, facebook, internet browsing, etc. during lectures and recitations.
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Department of Chemistry Fall Convocation
Friday, August 27, 2010; 2:10 p.m.
1352 Gilman Hall
“Atoms, Molecules and Bonds, a Multidisciplinary Journey, 400 B.C. to 2000 A.D.”
Prof. Klaus Ruedenberg
Department of Chemistry Iowa State University 2
Chemical Fundamentals: Introduction Importance of Chemistry in Our Society
• Health Issues: • Energy Issues: Research at ISU Ames Laboratory (US DOE) Catron Center for Solar Energy Research Center for Catalysis Center for Physical and Computational Mathematics Center for Sustainable Environmental Technologies Materials Preparation Center Microelectronics Research Center Midwest Forensics Resource Center • Environmental Issues:
Beyond the Molecular Frontier
, National Research Council, 2003 3
Chemical Fundamentals: Matter (1) Taxonomy
Pure Substances Mixtures 4
Chemical Fundamentals: Matter (2) Scale and States
• Nuclear: protons + neutrons • Atomic: • Molecular: • Nanoscale: nucleus + electrons aggregates of atoms oligomers, macromolecules • Microscopic: polymers, small crystals • Macroscopic: bulk materials, powders 5
Chemical Fundamentals: Matter (2) Scale and States
• Solids: • Liquids: • Gases: • Plasmas: • Supercritical Fluids: Carbon Dioxide 6
Chemical Fundamentals: Matter (3) Properties of Matter
Physical Properties: “Measured without changing the identity of the substance” Chemical Properties: CaC 2 (s) + H 2 O(l) CaO(s) + C 2 H 2 (g) 2 C 2 H 2 (g) + 5 O 2 (g) 4 CO 2 (g) + 2 H 2 O(l) 7
Chemical Fundamentals: Measurements (4) Units SI Units:
Seven fundamental quantities 1. Length (Meter) 2. Mass (Kilogram) 3. Time (Second) 4. Temperature (degree Kelvin) 5. Amount (Mole) 6. Electric Current (Ampere) 7. Luminous Intensity (Candela) Density = Energy = 8
Chemical Fundamentals: Measurements (5) Error
• Systematic (Determinate) Error • Random (Indeterminate) Error Source: H. Joyce, Millenium Mathematics Project
Curve Fitting (Regression)
(Propagation of Error) Source: J. Schreiner, MPI-Kernphysic X. Peng, et al., Nature 404 , 59-61(2000)
Gaussian Distribution
0.8
P
(
x
) 0.6
0.4
0.2
0.0
-6 -4 -2 = 0.5
0
x
= 1.0
= 2.0
2 4 6 Mean Value:
x
Standard Deviation: 9
Chemical Fundamentals: Measurements (6) Precision vs. Accuracy
Standard Deviation Mean Value =?= True Value
(1) (2) (3)
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Chemical Fundamentals: Measurements (7) Significant Figures
For each scale, report the value using the appropriate number of significant figures.
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Chemical Fundamentals: Atoms, Molecules, … (1) Important Experiments
• Faraday’s Experiments: • Thomson’s Experiment: • Milliken’s Oil-Drop Experiment: Source: Atom – The Incredible World Source: Atom – The Incredible World 12
Chemical Fundamentals: Atoms, Molecules, … (1) Important Experiments
• Rutherford’s Experiment: • Stern-Gerlach Experiment: Source: Encyclopedia of Science Source: Atom – The Incredible World 13
Chemical Fundamentals: Atoms, Molecules, … (2) Atomic Structure
Proton Neutron Electron Symbol 1 0 1
p
0 1 1
n e
Mass (g) 1.672 10 24 (1) 1.674 10 24 (1) 9.109 10 28 (“0”) Charge (coul) 1.602 10 19 (+1) 0.000 10 19 (0) 1.602 ( 1) 10 19 • ATOM = Spin (J sec) 5.273 10 35 (1/2) 5.273 10 35 (1/2) 5.273 10 35 (1/2) • NUCLEUS = Source: Dr. R.F.W. Bader, McMaster University, Canada.
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Chemical Fundamentals: Atoms, Molecules, … (2) Atomic Structure
Some key consequences: • # Protons (
Z
) – • # Electrons =
Core
electrons
Valence
electrons • # Neutrons Stability of Isotopes # Stable Isotopes 157 53 50 5 Protons Even Even Odd Odd Neutrons Even Odd Even Odd
Z A Sy
A Sy
Source: www.mc.maricopa.edu/~gilletti/CHM152/
NUCLEAR
.ppt
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Chemical Fundamentals: Atoms, Molecules, … (2) Atomic Structure
Stability of Isotopes: Radioactive Decay Alpha emission ( particle = 4 He nucleus) Beta emission ( particle = electron) Gamma radiation ( = high energy photons) Positron emission (mass of electron; positive charge) Electron (core) capture 16
Chemical Fundamentals: Atoms, Molecules, … (2) Atomic Structure
Stability of Isotopes
E
B
/A
Source: http://www.alaskajohn.com/physics/charts/binding_energy.jpg
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Chemical Fundamentals: Atoms, Molecules, … (2) Atomic Structure
Spin: response to a magnetic field E.g. 1 H is a
single proton
(spin = 1/2) Nuclear Magnetic Resonance (MRI) – organic and biomolecules… (Klaus Schmidt-Rohr) 2 H (= D, deuterium) is a
proton
+
neutron
(spin = 1) has different spin-derived physical properties than 1 H Chemical Properties: not significantly affected by isotopes, but … It takes more energy to break an O D chemical bond than an O H bond.
Why?
HO
H vs.
DO
D
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Chemical Fundamentals: Atoms, Molecules, … (3) Atomic Mass
Standard: 12 C atom Mass of 12 C atom (6 protons, 6 neutrons, 6 electrons) 1 amu = 1.661 10 24 g Many atomic masses are close to integer values, e.g., Some are not close to integers, e.g.,
Why not?
N (14.007 amu) Ca (40.078 amu) Cl (35.453 amu)
Isotopes
35 Cl 37 Cl
% / (100%) = Isotope Mass
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Chemical Fundamentals: Atoms, Molecules, … (3) Atomic Mass
Mass Spectrometer GC/LC-MS/MS Source: http://history.nasa.gov
Source: http://www.epa.gov
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Chemical Fundamentals: Atoms, Molecules, … (3) Atomic Mass
60 50 40 30 20 10 0 68 69 70 Mass Spectrum of Cl 71 72 73 Mass Number 2 74 75 76
Isotope Abundance
Let x = abundance of 35 Cl y = abundance of 37 Cl 21
Chemical Fundamentals: Atoms, Molecules, … (4) Microscopy: Can we “see” atoms?
Electron Microscope To “see” atoms, need light with wavelength ca. 0.1 nm (X-rays) Optical Microscopes: Electron Microscopes: Advantages: Disadvantages: Ames Laboratory, US Department of Energy Wilhelm Hall 22
Chemical Fundamentals: Atoms, Molecules, … (4) Electron Microscopy: SEM vs. TEM X-rays Incident e
Beam
Backscattered e Auger e Cathodaluminescence Secondary e
SAMPLE
Inelastically Scattered e Elastically Scattered e Unscattered e 23
Chemical Fundamentals: Atoms, Molecules, … (4) Electron Microscopy: SEM
Backscattered e :
X-rays Incident e
Beam
Backscattered e Auger e Cathodaluminescence Secondary e
SAMPLE
Secondary e : Auger e & X-rays: Factors affecting Image Brightness
Al-Cu alloy.
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Chemical Fundamentals: Atoms, Molecules, … (4) Electron Microscopy: SEM Incident Electron Beam
Auger e Secondary e Backscattered e Range of X-rays 25
Chemical Fundamentals: Atoms, Molecules, … (4) Electron Microscopy: TEM Incident e
Beam SAMPLE
Inelastically Scattered e Elastically Scattered e Unscattered e Elastically scattered e : Inelastically scattered e : 26
Chemical Fundamentals: Atoms, Molecules, … (4) Electron Microscopy: Examples Semiconductor Chip (ca. 100
150
m 2 ) Powder Particle (Quasicrystal: Y-Mg-Zn) ca. 30
m radius
Source: ISU Dept. of Materials Science and Engineering 27
Chemical Fundamentals: Atoms, Molecules, … (4) Electron Microscopy: Carbon Nanotubes
SEM Images TEM Image ca. 60 80 m 2 10 nm inner diameter 9 concentric walls Source: http://www.nano-lab.com/imagegallery.html
ca. 1.5 2 m 2 (1500 2000 nm 2 ) 28
Chemical Fundamentals: Atoms, Molecules, … (4) Electron Microscopy: Material Issues in Nuclear Reactors
Pressurized water in a closed coolant loop carries intense heat generated by fission reactions in nuclear fuel rods (in the reactor core) to steam generators. There, heat is transmitted to water in a separate closed loop to form steam, which drives the turbine (to generate electricity), cools, condenses, and returns to the steam generators.
To
stainless steel
specimens exposed to a nuclear reactor environment, an oxygen weight difference of just 0.04% causes the oxygen-richer material (bottom) to become brittle and pocked with micrometer-sized grains.
The other sample retains its structural integrity, as seen in these SEM images.
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Chemical Fundamentals: Atoms, Molecules, … (4) Microscopy: Imaging Techniques
Source: A. B. Ellis, ACS, 1993 30
Chemical Fundamentals: Atoms, Molecules, … (4) Microscopy: Imaging Techniques
Source: TU-Vienna STM Tip (200 kV incident electrons) Bar length: ca. 20 nm Source: Purdue Univ.
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Chemical Fundamentals: Atoms, Molecules, … (4) Microscopy: Imaging Techniques -- STM
Source: M.D. Porter, ISU S 8 32
Chemical Fundamentals: Atoms, Molecules, … (4) Microscopy: Imaging Techniques -- Lithography
Subsurface H atoms in Pd – PSU arises from Pd atoms rising to make “room” for interstitial H atoms. H atoms find sites by using voltage impulses from an STM tip.
Letter height = ca. 0.3 Å; Letter width = ca. 40 Å.
Image by: E. H. Sykes, L. Fernandez, B. A. Mantooth, P. Weiss 33
Chemical Fundamentals: Atoms, Molecules, … (4) Microscopy: Improved AFM Capabilities
Scanning tunneling microscopy (STM) has limited ability to distinguish individual atoms and bonds. In the past, AFM has done no better at resolving atomic-scale features, producing only fuzzy images of individual molecules.
C 22 H 14 CO
-tip AFM image (bottom) reveals atoms and bonds of pentacene (top), whereas conventional STM image (center) cannot. Scale bars are 5 Å.
Chemical and Engineering News,
August 31, 2009, p. 6 Gross, et al.
Science 2009 ,
325
, 1110 34
Chemical Fundamentals: Atoms, Molecules, … (5) The Periodic Table H Li Na K Rb Cs Fr Be Mg Ca Sr Ba Ra Sc Y La Ac Ti Zr Hf Rf V Nb Ta Db Cr Mo W Sg Mn Tc Re Bh Fe Ru Os Hs Co Rh Ir Mt Ni Pd Pt 110 Cu Ag Au 111 Zn Cd Hg 112 B Al Ga In Tl C Si Ge Sn Pb N P As Sb Bi O S Se Te Po F Cl Br I At He Ne Ar Kr Xe Rn Lanthanides: Actinides: Ce Th Pr Pa Nd U Pm Np Sm Pu Eu Am Gd Cm Tb Bk Dy Cf Ho Es Er Fm Tm Md Yb No Lu Lr Metals Metalloids (Semiconductors) Nonmetals
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Chemical Fundamentals: Atoms, Molecules, … (6) Combining Atoms:
Do
free atoms
exist?
H Li Na K Rb Cs Fr Be Mg Ca Sr Ba Ra Sc Y La Ac Ti Zr Hf Rf V Nb Ta Db Cr Mo W Sg Mn Tc Re Bh Fe Ru Os Hs Co Rh Ir Mt Ni Pd Pt 110 Cu Ag Au 111 Zn Cd Hg 112 B Al Ga In Tl C Si Ge Sn Pb N P As Sb Bi O S Se Te Po F Cl Br I At He Ne Ar Kr Xe Rn Ce Th Pr Pa Nd U Pm Np Sm Pu Eu Am Gd Cm Tb Bk Dy Cf Ho Es Er Fm Tm Md Yb No Lu Lr
Aggregates: • Diatomic Molecules • Rings or Chains • Layers • Three-dimensional Nets • Three-dimensional Sphere Packings (Everything else…) 36
Chemical Fundamentals: Atoms, Molecules, … (6) Combining Atoms:
Ions Two atoms interact with each other by… (a) (b)
H Li Na K Rb Cs Fr +1 Be Mg Ca Sr Ba Ra +2 Sc Y La Ac +3 Ti Zr Hf Rf Ce Th V Nb Ta Db Cr Mo W Sg Mn Tc Re Bh Fe Ru Os Hs Co Rh Ir Mt Ni Pd Pt 110 Cu Ag Au 111 Zn Cd Hg 112 B Al Ga In Tl C Si Ge Sn Pb N P As Sb Bi O S Se Te Po
2 F Cl Br I At
1 He Ne Ar Kr Xe Rn 0 Pr Pa Nd U Pm Np Sm Pu Eu Am Gd Cm Tb Bk Dy Cf Ho Es Er Fm Tm Md Yb No Lu Lr
“Cations” (net positive charge)… “Anions” (net negative charge)… Polyatomic Ions: 37
Chemical Fundamentals: Atoms, Molecules, … (7) Chemical Formulas
(Symbolism) (a)
Empirical Formulas
– (b)
Molecular Formulas
– (c)
Metallurgical Formulas
–
(8) Nomenclature:
see pages 1-24 to 1-27 in 201 Notes 38