CHEM Exam 3 Study Guide
CHEM Exam 3 Study Guide CHEM 211-002
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This 0 page Study Guide was uploaded by Briana Marcy on Thursday December 3, 2015. The Study Guide belongs to CHEM 211-002 at George Mason University taught by Paul Cooper in Summer 2015. Since its upload, it has received 230 views. For similar materials see General Chemistry 1 in Chemistry at George Mason University.
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Date Created: 12/03/15
CHEM 211 EXAM 3 Study Guide Chapters 7 8 9 10 CH 7 Quantum Theory and Atomic Structure The Wave Nature of Light The wave properties of electromagnetic radiation are described by three variables frequency cycles per second wavelength the distance a wave travels in one cycle amplitude the height of a wave crest or depth of a trough the speed of light is a constant 30010quot8 ms in a vacuum Energy and Frequency A solid object emits visible light when it is heated to about 1000 K This is called blackbody radiation The C00rand the intensity of the light changes as the temp changes Color is related to wavelength and frequency while temperature is related to energy Planck proposed that one certain quantities of energy can be emitted or absorbed The Quantum Theory of Energy Any object including atoms can emit or absorb only certain quantities of energy hv Energy is quantized it occurs in xed quantities rather than being continuous Each xed quantity of energy is called a quantum hv An atom changes its energy state by emitting or absorbing one or more quanta of energy AE nhv where n can only be a whole number the smallest change being where n1 AEatom hv Ephoton The Bohr Model of the Hydrogen Atom Bohr s atomic model postulated the following o The H atom had only certain energy levels which Bohr called stationary states 0 Each state is associated w a xed circular orbit of the electron around the nucleus 0 The higher the energy level the farther the orbit is from the nucleus 0 When the H electron is in the rst orbit the atom is in its lowest energy state called the ground state 0 The atom does not radiate energy while in one of its stationary states 0 The atom changes to another stationary state only by absorbing or emitting a photon The energy of the photon hv equals the difference between the energies of the 2 energy states When the E electron is in any orbit higher than n1 the atom is in an excited state Matter and energy are alternate forms of the same entity ALL MA39ITER exhibits properties of both particles AND waves Heisenberg39s Uncertainty Principle Heisenberg s Uncertainty Principle states that it is not possible to to know the position and momentum of a moving particle at the same time The more accurately we know the speed the less accurately we know the position and vice versa QUANTUM NUMBERS AND ATOMIC ORBITALS An atomic orbital is speci ed by three quantum numbers The principal quantum number n is a positive integer The value of n indicates the relative size of the orbital and therefore its relative distance from the nucleus The angular momentum quantum number I is an integer from 0 The value of indicates the shape of the orbital The magnetic quantum number m1 is an integer with values from to The value of m1 indicates the spatial orientation of the orbital CH 8 Shielding and Orbital Energy 0 Electrons in the same energy level shield each other to some extent 0 Electrons in inner energy levels shield the outer electrons very effectively 0 The further from the nucleus an electron is the lower the Zeff for that particular electron Splitting of Levels into Sublevels Each energy level is split into sublevels of differing energy Splitting is caused by penetration and its effect on shielding For a given n value a lower I value indicates a lower energy sublevel Order of sublevel energies slt plt dlt f Building Orbital Diagrams The aufbau principle is applied electrons are always placed in the lowest energy sublevel available The exclusion principle states that each orbital may contain a maximum of 2 electrons which must have opposite spins Hund39s Rule specifies that when orbitals of equal energy are available the lowest energy electron con guration has the maximum number of unpaired electrons with parallel spins
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