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Jordan University College of Science Chemistry Department Amman - Jordan First Semester 2011/2012 Course: Quantum Chemistry 0333741 Instructor: Prof. Dr. Khader A. Al-Janaideh Objectives: Matter and Energy are the components of the universe we are living in. Their corresponding smallest building units are atoms and photons respectively. Their motion has been of concern of scientists of physics and chemistry. Unlike the motion of large particles (undergo continuous motion) which can be followed by Newton's laws of mechanics, the motion of tiny particles, like electrons in atoms, molecules and atoms in molecules, etc. (quantized motion) can be followed by wave or quantum mechanics. Since the photons of electromagnetic radiation (emr) like : -ray, X-ray, U.V-visible, I.R, microwave, radar waves, radio waves are waves of different frequencies and/or energies, these waves can be used to follow the motion of tiny particles like motion of electrons in atoms and molecules and other kinds of motions present in molecules : As example : 1. X-ray radiation can be used to follow motion of inner electrons in atoms and molecules. This leads to X-ray spectroscopy. 2. U.V.-visible radiation can be used follow motion of valence electrons in atoms and molecules. This leads to U.V.-Visible spectroscopy. 3. I.R and microwave radiators can be used to follow vibrational and rotational motions of molecules respectively. These lead to I.R. and microwave spectroscopy. 4. The radar and radio waves are used to follow flip motion of spin of electrons and protons, respectively. These lead to electron spin resonance (ESR) and nuclear magnetic resonance (NMR) spectroscopy, respectively. The field of science that deals with wave motion of systems like electrons, atoms, molecules, etc. is called wave mechanics or quantum mechanics. Quantum mechanics has its own postulates and mathematical laws that can be applied to each system mentioned above in order to follow and understand their motion during transition from the ground state to the excited state. The energy difference between these states is simply, E = h which is very small in case of NMR transitions and becomes large in I.R. and very large in case of U.V.-visible transitions. The energy of these (ground and excited) states can be found by solving Schrödinger equation, H, = E (H: is the energy operator, is the wave function and E is energy) which was derived from the wave-equation of motion. Each system has its own H and depending on the motion under study. Our goal is to obtain H and and E for each system. To achieve our goals we will study three models of motions : 1. 2. 3. Particle in a box model : A model used to study motion of particle on a line (1-D), on a surface (2-D) and in a space (3-D). These models will be applied to motion of electrons in conjugated molecules like butadiene and benzene, etc. The validity of the theoretical calculation results can be checked by comparing to electronic absorption spectra results. Rigid rotor model : A model used to study rotation of diatomic molecules This will lead us to understand rotational spectra (microwave spectra) of molecules. Harmonic oscillator (H.O.) model : A model used to study vibration of diatomic molecules. This will lead us to understand the vibrational spectra (I.R. spectra) of molecules. The validity of the theoretical calculation results can be checked by refereeing to experimental results obtained by spectroscopic measurements. Deviation of real system as compared to ideal system (models) leads to modification of the model for purposes of improvement of the calculation results. Sometimes approximation methods are used to achieve these improvements. This course is designed in a way to achieve the above goals in a systematic way according to the following contents : Content 1. 2. 3. 4. 5. 6. 7. 8. Mathematical review. Structure of atom and failure of classical mechanics in explaining experimental observations like atomic spectra, etc. Quantum mechanics and the role of contributions of Bohr, Planck, Einstein, de Broglie, Heisenberg and Shrodinger. Schrödinger equation and postulates of quantum mechanics (Q.M.). Application of postulates of Q.M. to various motions : a. Particle in a box model. b. Rigid rotor model and microwave spectroscopy. c. H.O. model and vibrational spectroscopy. Operators and angular moment (tools of Q.M.). The electronic structure of atom : a. one electron atom : H- and H-like atoms. b. many electrons atoms : He-atom etc. Molecular orbital theory and application to diatomic molecules and molecular spectroscopy. References : 1. 2. 3. 4. Quantum Chemistry by Ira N. Levine 5th Edition. 2000, Prentice-Hall, Inc. Quantum Chemistry by D. A. McQuarrie 1983. Molecular quantum mechanics by Peter Atkins and R. Friedman 4th Ed. 2005. Fundamental of Molecular Spectroscopy by C. N. Banwell, 3rd Ed. 1983. Evaluation of the Course : Home works: : There will be 6 – 9 problem sets as home work, assignments You must handle out the solution of problem sets on time. A key for each problem set will be given on time too. Exams : 1. 2. 3. 4. Drop in Quizzes First Exam. Second Exam. Final Exam. 5% ~ 30 % ~ 30 % 40 %