“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.

1

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)

10

Chemical Fundamentals: Measurements (7) Significant Figures

For each scale, report the value using the appropriate number of significant figures.

11

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.

14

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

15

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

17

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

18

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

19

Chemical Fundamentals: Atoms, Molecules, … (3) Atomic Mass

Mass Spectrometer GC/LC-MS/MS Source: http://history.nasa.gov

Source: http://www.epa.gov

20

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.

24

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.

29

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.

31

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

35

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