Slides for Lecture Chapter 8 Part I_1

Slides for Lecture - Molecularity Molecularity CH1010 Chapter 8 Part I Quantum Theory and Atomic Structure James P Dittami The Schrödinger

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Unformatted text preview: Molecularity Molecularity CH1010 Chapter 8 Part I Quantum Theory and Atomic Structure James P. Dittami The Schrödinger Equation The Schr Studies Reveal The Schrödinger Equation Wave & particle properties of energy and light Electrons emit/absorb energy in fixed packets Provides a set of descriptors for each and every electron in an atom Defines the region or orbitals where they can be found, and their energy, size and shape Orbitals for the Hydrogen Atom Orbitals for the Hydrogen Atom Described by the quantum numbers that arise from the Schrödinger Equation n Principal Quantum no. 1, 2, 3 … l Angular momentum Quantum no. 0 to n­1 Relates to the Energy and Size of the orbital ml Magnetic Quantum no. –l to l Relates to the Shape of the orbital – s, p, d, f Provides information on the Orientation in space Orbitals for the Hydrogen Atom Orbitals for the Hydrogen Atom Energy is determined by quantum no. n All orbitals with same Quantum no. have the same energy. They are said to be degenerate Electrons populate the lowest energy orbitals­ this is the ground state Electrons absorb energy to go into higher E orbitals: excited state Figure 7.18 Orbital Energy Figure 7.18 Orbital Energy Levels for the Hydrogen Atom Electron Spin: the Pauli Electron Spin: the Pauli Principle Electrons possess magnetic moment When placed in a magnetic field they can adopt either of two orientations Electrons behave like tiny magnets Recall from Physics­ spinning charges produce a magnetic field Aligned with the field Aligned against the field Figure 7.19 A Picture of the Figure 7.19 A Picture of the Spinning Electron Fourth Quantum No. ms Fourth Quantum No. Electrons have charge and magnetic moment Conclusion­ electrons have spin ms the fourth quantum no. with value spin = +1/2 or ­1/2. Pauli’s Exclusion Principle Pauli’s Exclusion Principle “In a given atom, no two electrons can have the same set of four quantum numbers (n, l, ml, ms)” Since electrons in the same orbital have the same values of n, l, ml, this principle says they must have different values of ms Also, since ms = ± ½ (only two allowed values): there can only be 2 electrons/ orbital Polyelectronic Atoms Polyelectronic Atoms Revise our picture of orbital energy levels Electron ­ electron repulsion in the atom Inner electrons shield outer electrons from the nucleus Revisit the energy level diagram for Hydrogen to reflect these considerations For a given value of n not all electrons are of same energy The Orders of the Energies of the Orbitals in The Orders of the Energies of the Orbitals in the First Three Levels of Polyelectronic Atoms Figure 2.10 The modern periodic table. Figure 8.11 A periodic table of partial ground-state electron configurations Fig. 8.13 Fig. 8.13 ...
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This note was uploaded on 02/14/2011 for the course CH 1010 taught by Professor Kumar during the Spring '06 term at WPI.

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