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Chemistry 1410.005—INTRODUCTORY LECTURE Fall, 2010

Chemistry 1410.005—INTRODUCTORY LECTURE Fall, 2010 Instructor: Prof. J. A. Kelber (x3265; kelber@unt.edu ) Office: 232 Science Research Bldg. Office Hours T (3-5) or by appointment Teaching Asst .: TBA Text: Principles of Chemistry, the Molecular Science

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Chemistry 1410.005—INTRODUCTORY LECTURE Fall, 2010

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  1. Chemistry 1410.005—INTRODUCTORY LECTURE Fall, 2010 Instructor: Prof. J. A. Kelber (x3265; kelber@unt.edu) Office: 232 Science Research Bldg. Office Hours T (3-5) or by appointment Teaching Asst.: TBA Text: Principles of Chemistry, the Molecular Science (Moore, Stanitski and Jurs)—required

  2. Lecture Outline About the Professor About the Course How to get a good grade What we will cover this semester Stuff (mainly from Chapt. 1, but presented in a confusing manner)

  3. Prof. Jeffry A. Kelber BS (with honors) 1975, CalTech (Chemistry) Ph.D. 1979 , Univ. of Illinois/Champaign Urbana (advisor, Prof. G. D. Stucky) 1979-1990; member of technical staff: Sandia National Laboratories 1990-present, Chemistry Faculty, Univ. of North Texas Current Rank: Regents Prof. of Chemistry Publications ~ 150 Research Area: Chemistry and Physics of Surfaces and Thin Films

  4. About this course….YOUR GRADE • Quizzes: (10% ) every Thurs. (usually), multiple choice, 10-15 minutes each • Exams: (25% each x 2 = 50%) 1 hour, multiple choice in class, NO EXAMS WILL BE DROPPED. • Cumulative Final (40%) Given during finals week (12/11; 10:30 AM here) • Extra-Credit—None! • Yahoo! No Homework!!? WRONG!!!! • Homework will be assigned weekly • Homework will be discussed the following week in recitation • Homework will NOT be Graded. However, quiz and test questions will often be drawn from the homework.

  5. How to get a good grade…………… • Have learned and remembered something from your high school chemistry class • (exponents, logs, trig… dimensional analysis(maybe)) • Read the Chapter before the week it is discussed! • Keep up with homework, lectures, etc. • If you have questions or problems, consult • A. Classmates • B. Professor (if available… that’s what office hours are for, but I will be out of town a lot) • C. The CRC • D. The TA

  6. What this course is about: • Fundamentals of chemistry • * atoms molecules chemical reactions • ** Elementary understanding of chemical bonding/structure • Learning to think about nature • Memorization generally not helpful • Analytical skills, critical thinking important • Imagination and creativity

  7. About the exams: • Closed book study before the exam • Questions will involve analytical skills, not memorization! • Do NOT memorize physical constants, etc. You will be given that info on the exam • No computers, and cell phones off during the exam! • Calculators (no cell phones) are permitted. Should have log, exp, trig functions • Exams will be hard, but graded on a curve • No exams will be dropped!

  8. Lectures and Recitations: Why Both: Lecture: *Emphasize and explain basic concepts **Not all topics covered in Lecture! ***Therefore, read the book:  Read the chapter before we begin  Re-read the chapter after Recitation: *Homework and discussion **Understanding comes from homework and quizzes

  9. This Semester: • Chapt. 1 Nature of Chemistry (read outside of class) • Chapt. 2 Atoms and Elements –Rutherford model of the atom, and its consequences • Chapt. 3 Chemical Compounds • Chapt. 4 Quantities of Reactants and Products (the Mole Concept, again, review for some of you) • Chapt. 5 Chemical Reactions (mainly in solution): Generally Accepted Accounting Practices for Mother Nature. • Chapt. 6 Energy and Chemical Reactions: Why some rxns give off heat and others adsorb it…(elementary thermodynamics) • Chapt. 7 Electronic Configurations and the Periodic Table : Rudimentary quantum mechanics, orbitals, • Chapt. 8 Chemical Bonding : How electronic structure affects chemical bonding, periodic trends in properties • Chapt. 9 Bonding and Molecular Structures • Chapt. 10 Gases and the Ideal Gas Law (PV = nRT) • Chapt. 11 Metals, Liquids and Semiconductors (optional)

  10. Travel Schedule, Fall 2013 Sept. 3-6: Portland, OR: Intel/SRC review Sept. 23-30 Shanghai and Xi’an, China— seminars at Fudan, Nanotechnology Conf., October 21-22 (?) Seminar at Univ. of Nebraska-Lincoln Oct. 28-Nov. 1 American Vacuum Society Symposium, Long Beach, CA • Why is this necessary? • Communication of research • Obtaining financial resources to support more (graduate and undergraduate) students doing research…

  11. A word about memorization…. Forget it! • Science puts a premium on imagination and deduction • You will be asked to think quite a bit, rather than memorize formulae. • Tests will be multiple choice and open book, but NOT easy • WORK THE HOMEWORK PROBLEMS YOURSELF, THEN (IF NECESSARY) GET HELP: • FROM YOUR TA • FROM THE CRC • FROM YOUR PROFESSOR

  12. The Development of Modern Chemistry Bardeen, Brattain, Schockley, Transistor (1947) Planck, quanta, 1900 Atom Bomb (1945) Haber, Langumir: Catalysis and surface chemistry Boltzmann, kinetic theory of gases (1870’s) DeBroglie, Davisson and Germer, wave nature of the electron (1925-27) J. J. Thomson, discovery of the electron (1897) Atomic theory (Dalton,1803) Pauling, Mulliken, et al. chemical bonding Rutherford model of the atom (1913) Chemical bonding and nuclear physics/chemistry B ohr model (1913) 1900 1800 Heisenberg, Schroedinger, Dirac, Born New quantum theory (1925-30) Dalton, Henry Electricity and magnetism Mendeleev, periodic table (1871) Einstein, photoelectric effect (1905) Crick, Watson, Franklin DNA double Helix (1952) Atomic theory, classical physics Quantum theory

  13. 1952, Teal and Buehler (Bell Labs) publish paper on production of ultra pure Si; the modern transistor is born 1947, Bardeen, Shockley and Brattain, form a research group at Bell Labs to develop solid state switches and amplifiers: Develop the modern transistor using germanium! 1925-1945: Birth of solid state physics, chemistry; understanding the behaviors of electrons in solids Mott, Pierls, Pauling, Seitz solid state physics The “Invention” of the Transistor 1925: Birth of the new quantum theory; Understanding electrons in matter 1913: Rutherford model of the atom/ Bohr Theory 1900: Planck/quantized photon energy

  14. Moral: Most Great modern “inventions” are not really invented… They are the culmination many different advances. Max Planck had no idea that quantum physics would yield the transistor and … high speed computing molecular biology lasers modern metallurgy the internet Facebook(!?) and……… Do Funding Officers and Agencies understand this? Not always! Example: The “war” on cancer: We spend lots of money on minor clinical advances, but underfund basic research that could lead to real breakthroughs (NYT-2009)

  15. Since 1947: The morphing of the transistor: From electronics to microelectronics to nanoelectronics 1 transistor/chip 1 billion/chip

  16. Moore’s ‘Law’ # of Transistors on a chip doubles ~ every 2 years (Moore’s Law): Transistors (and interconnects) need to get smaller! From IEEE.org/Intel Logic devices Number of transistors on a chip > 1 x 109 = 1,000,000,000 (1 billion) (one followed by 9 zeroes)

  17. The modern field-effect Transistor I Vapp Vapp Gate oxide thickness (d) ~ 1 nm e- Channel length (L) =65 nm http://commons.wikimedia.org/wiki/File:Scheme_of_metal_oxide_semiconductor_field-effect_transistor.svg

  18. What are nanometers? Atomic diameters? • Scientific Notation? • Dimensional Analysis???

  19. Let’s consider a piece of Si about ½ inch x ½ inch: 0.5 in = 5 x 10-1 in 0.5 in = 5 x 10-1 in What’s the total area? A = LxW = 0.5 in x 0.5 in = 5 x 10-1 in x 5 x 10-1 in = (rearranging) 5 x 5 x 10-1 x 10-1in x in NOTE 10A x 10B = 10A+B therefore, A = 25 x 10-2 in2 = 2.5 x 10-1 in2

  20. Dimensional Analysis: How can we convert from in2 to cm2? Conversion Factor: 1 in = 2.54 cm 1 in2 = 1 in x 1 in = (1 in x 2.54 cm/in) x (1 in x 2.54 cm/in) = 2.54 x 2.54 cm2 = 6.45 cm2 Our chip has a total area of 6.45 cm2 6.45 cm2

  21. There are ~ 1 billion (1 x 109) transistors on a chip. What is the average area of each transistor? We want answer in terms of cm2/transistor. So let’s divide the total chip area by the number of transistors! Area/transistor = [total chip area]/[109 transistors] = 6.54 x 10-9 cm2/transistor This is a bit hard to visualize, so let’s convert to atomic dimensions and then to atoms!

  22. Let’s try units of nanometers (nm) 1 cm = 10-2 meters (m); 1 m = 102 cm 1 nm = 10-9 m x 102 cm/m = 10-7 cm 1 nm2 = (10-7 cm) x (10-7 cm) = 10-14 cm2 Area/transistor = 6.54 x 10-9 cm2/transistor / [10-14 cm2/nm2] = 6.54 x 10-9 x 1014nm2/transistor = 6.54 x 105nm2/transistor

  23. About how many Si atoms is that? Fact: Areal Density of Si atoms on Si(100) is ~ 1015 atoms/cm2 1015 atoms/cm2 x [10-7 cm/nm]2 x 6.54 x105 nm2 = 1015 atoms/cm2 x 10-14 cm2/nm2 x 6.54 x 105 nm2 = 6.54 x 106 atoms/transistor (estimate) ~ 107 atoms/transistor This sounds like a lot, but the number of atomic diameters for the L and W of a transistor is then ~ √107 = (107)1/2 atoms on a side! (107)1/2 = (10 x 106)1/2 = (10)1/2 x (106)1/2 ~ 3.12 x 103 atoms on a side

  24. transistor 1000 atoms 1000 atoms

  25. Transistors get smaller…. Channel length 65 nm =650 angstroms: ~ 200-300 atomic diameters!!! Gate oxide < 1.2 nm thick ~ 5 silicon atoms thick! From IEEE.org/Intel logic Devices

  26. What happens at atomic dimensions… Oxide thickness ~ electron wavelength (d ~λ) The electron “leaks out”: Leakage current lowers battery life, limits on/off state detection. e-

  27. What to do? Change gate oxide from SiO2 to HfSiOx (Hafnium silicate) Greater polarizeability oxide can be made thicker! (long story…) First research papers…1990’s (e.g., review by Wilk and Wallace, 1999) In production…2008 This invention took two decades and lots of people!

  28. About the Future….? Continued shrinkage of transistor dimensions hindered by wave nature of electrons (λ d) Can we develop materials/devices that take advantage of the quantum behavior of electrons??? Single atomic layer of graphite “graphene” Rapid electron conduction at room temperature Many other amazing properties (see Geim, et al; also deHeer group, Georgia Tech/2004), also an episode of TV’s “Big Bang Theory”) lbl.gov

  29. Beyond the Transistor: Non-volatile logic/memory elements: Based on spin? (Graphene instead of InAs??) S. Suguhara and J. Nitta; Proc. IEEE 98 , 2125 (2010)

  30. Beyond the transistor and spin-transistor: logic gates based on spin devices (Here, magnetic tunnel junctions) Velev, et al., Surf. Sci. Rep.63, 400 (2008) Richter, et al: Appl. Phys. Lett. 80, 1291 (2002)

  31. Summary: Scientific Discovery is a Long Road, and no one knows where it will lead. (You can’t predict the future!) The Transistor took 50 years, and the end is not in sight **new materials ***spin vs. charge (spintronics) ****neural networks (networks that learn) ????????

  32. Conclusion: • Memorization? ….fughedaboudit! (Tony Soprano) • You should know or learn: • dimensional analysis • scientific notation • get a feel for problem solving • Example…..

  33. Question: Given that the areal density of Si is 1015 atoms/cm2, Estimate the atomic diameter of a Si atom in angstroms 1 cm 1015 Si atoms 1 cm

  34. Second Problem: Mass of a hydrogen atom: 1 atomic mass unit (amu) Mass of 1 mole of atomic H: 1 gr. 1 mole of anything = 6.02 x 1023 of those things. Problem 2: calculate the mass of a H atom in grams From Chapter 1 Probs. 14, 26, 27, 63

  35. For Tuesday • Work assigned problems (handout) • Read Chapts 1 and 2 of text

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