Transcription of Physical Chemistry - Kocherzhenko
1 Physical Chemistry A Very brief Introduction Aleksey Kocherzhenko March 14, 2013". What Is Physical Chemistry ?". Physical Science". is that department of knowledge which relates to the order of nature, or in other words, to the regular succession of events.". All Chemistry is a branch of Physical science". What Is Physical Chemistry ?". The name of Physical science, however, is often applied in a more or less restricted manner to those branches of science in which the phenomena considered are of the simplest and most abstract kind, excluding the consideration of the more complex phenomena.
2 ". ". James Clerk Maxwell, Matter and Motion , 1876! What Is Physical Chemistry ?". Chemistry started out as an empirical science". Synthetic chemists: think in terms of functional groups". Biochemists: concerned with the functionality of large molecules". Physical chemists: often look at phenomena at an atomic and even subatomic level describe phenomena in an abstract mathematical way". What Is Physical Chemistry ?". Traditionally included are:". ". Thermodynamics". Kinetics". Quantum mechanics". ". as applied to molecular-level phenomena". A Great Textbook".
3 D. A. McQuarrie and J. D. Simon! Physical Chemistry : A Molecular Approach University Science Books, 1997". Quantum Mechanics and Chemistry ". R". ortho! meta! para! Reactivity is determined by orbital symmetry ". in many cases, so are functional properties!". Orbits vs. Orbitals". Ernest Rutherford" Thomson". Planetary atomic model" Plum pudding atomic model". Orbits vs. Orbitals". The absorption/emission spectra of atoms are discrete, not continuous!".. Rydberg's formula:" 1 2 1 1. = RZ. vac n21 n22. Orbits vs. Orbitals". Centripetal force:" me v 2 Ze2 Coulomb = force r 4 "0 r2.
4 Angular momentum quantization:" me vr = n~. Niels Bohr" Principal quantum number Reduced n = 1, 2, 3, Planck's constant ). Ze2 me v 2 1 Ze2. E= + =. 4 "0 r | {z 2 } 2 4 "0 r | {z }. U T.. n~ 4 "0 ~ 2. n2. where" r= =. me v e2 me Z. Model of an H-like atom" Bohr radius rB . A. Orbits vs. Orbitals". Energy levels of a hydrogen-like atom: " Correct absorption frequency:".. e me Z 2. 4. E = E2 E1 = h . E=. 8"20 h2 n2 Planck constant: h = 2 ~. | {z } Rydberg constant, R. eV. E (eV)". n = " E = 0" ( vac = c). ". n = 4". n = 3" E = ". n = 2" E = ". to satisfy Rydberg's formula:".
5 1 2 1 1. = RZ. n = 1". + E = ". vac n21 n22. Orbits vs. Orbitals". Photoelectric effect:". Interference: light is a wave" light consists of particles?" Louis de Broglie". Light (and everything else) has both particle-like and wave-like properties". h De Broglie wavelength:" =. p Or:" p = ~k, k = 2 / (angular wavenumber)". E = ~!, ! = 2 (angular frequency)". Particle-wave duality". Orbits vs. Orbitals". Particle in centrosymmetric potential:". Old quantum theory ". E (eV)". n = " E = 0". ". n = 4". n = 3" E = ". n = 2" E = ". n = 1" E = ". + Wave in centrosymmetric potential:".
6 New quantum theory ". Orbits vs. Orbitals". E (eV)". n = " E = 0". ". n = 4". n = 3" E = ". n = 2" E = ". n = 1" E = ". + 1) Electrons in atoms are found in stable (time-independent) states". 2) Electrons behave as waves". ) Stable electronic states (orbitals) are standing waves". What a Typical PChem/QMech Course Covers:". 0) Mathematical background and notation! 1) Foundations of quantum mechanics! Postulates, equation of motion, stationary states". 2) Simple model systems! Particle-in-a-box, harmonic oscillator, hydrogen atom, barriers". 3) Multi-electron atoms!
7 Approximate methods, spin". 4) Molecules! Orbital hybridization, chemical bonding". 5) Spectroscopy! Degrees of freedom, types of spectroscopy to probe them". 6) The paradoxes of quantum mechanics and its relationship to classical mechanics!
