25 Ionic and Covalent Bonding - Chapter 9 Electronic...

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Chapter 9 1 Presentation of Lecture Outlines, 9–1 Electronic Configuration - review Solution to the Schrodinger equation for an electron in an atom. The „ confinement ‟ of an electron results with discretization of the electron properties This is resulting with several types of quantum numbers These numbers describe the state of the electron ' ' ' ' ' ( , , ; , , , ) ( , , ) ( , , ) ( , , ) ( ) ls l s n l m m E x y z n l m m x y z x y z x y z spin Presentation of Lecture Outlines, 9–2 Electronic Configuration - review The electron state is described by discrete values - quantum numbers. Each set of numbers corresponds to a solution of the hydrogen atom . These solutions are slots to use for occupying electron in multielectron systems Pauli principle and Hund rule as guides. Aufbau principle and sub shell notation Presentation of Lecture Outlines, 9–3 Review- Atomic properties Atomic Radii Ionic potential Electron affinity Periodic Properties – ionization energy Ionization energy: energy needed to remove an electron cation formation. first ionization energy : minimal energy needed to remove the first electron This is the (outermost) electron. For lithium atom, the first ionization energy is related to: e ) s 1 ( Li ) s 2 s 1 ( Li 2 1 2 Ionization energy = 520 kJ/mol Presentation of Lecture Outlines, 8–4 Ionization potential Alkali metals reactivity is marked by tendency to lose an electron low potentials Noble gases – expect higher potential Presentation of Lecture Outlines, 9–5 Periodic Properties- ionization energy Follows the trend in size  more difficult to remove an electron that is closer to the nucleus Within a period ionization energies increase with Z. Exception upon emptying a sub shell: as 2s 2 2p 1 , etc (see figure) Also 2s 2 2p 4 is an exception Within a descend in group: ionization energy decreases Presentation of Lecture Outlines, 9–6
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Chapter 9 2 Presentation of Lecture Outlines, 9–7 Electron Affinity Electron Affinity- tendency to attract electron. The more negative the electron affinity more stable the formed negative ion. general trend: upper (less shielding) right (more positive) higher EA lower left the least electron affinities. Less EA when a new sub shell/half sub shell is occupied There are more exceptions: EA is harder to predict than IP. Need more accurate treatment of electron correlation. Presentation of Lecture Outlines, 9–8 Electron affinity-Periodic Properties E lectron affinity : energy change due to adding an electron to a neutral atom in the gaseous state. For a chlorine atom, the first electron affinity is: ) p 3 s 3 ] Ne ([ Cl e ) p 3 s 3 ] Ne ([ Cl 6 2 5 2 Electron Affinity = -349 kJ/mol •Group IA filled ns shell – moderate EA •Group IIA start to fill np positive EA!
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This note was uploaded on 04/07/2010 for the course CHEMISTRY chem 130 taught by Professor Mr during the Spring '10 term at University of Michigan.

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25 Ionic and Covalent Bonding - Chapter 9 Electronic...

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