Chapter 8 Ebbing an Gammon Electronic Configuration and Periodicity From Chapter 7 What is the Pauli exclusion principle Write out a complete n l ml ms table for sulfur What is Hund s rule Define the term paired electrons Name the energy shells used by sulfur Name the subshells being used by sulfur How many electrons needed to fill a 5g subshell Electron Configurations Using spdf Notation I suspect for most of you the material in Chapter 7 was mostly new In Chapter 8 we will be covering the so called spdf method of electronic energy notation I suspect in this case most of you have had some exposure to this method It is important to remember that I expect you to be able to connect the n l ml ms method to the spdf method To do this you must be clear on the interrelationships between n l and ml 1 n l of orbitals of electrons 1 0 1 2 2 0 1 2 1 3 6 0 1 2 1 3 6 2 5 10 0 1 2 1 3 6 2 5 10 3 7 14 0 1 2 1 3 6 2 5 10 3 7 14 4 9 18 3 4 5 Show how the values in this table are connected to the 4 areas of electron grouping in the periodic table Show how the value of n changes in the periodic table Introduction to spdf notation for electronic energies The spdf method of electron energy notation and its relationship to the l Q N l 0 1 2 3 4 5 6 7 8 9 subshell name s p d f g h i j k l max of electrons 2 6 10 14 18 2 Show connection between periodic table and spdf notation for electronic energies aka electronic configurations Ground State Electronic Configurations What is meant by the terms Ground state electronic configuration Excited state electronic configuration Write out the complete ground state spdf electronic configuration for O S Ge Pb V Using rare gas cores give the ground state electronicconfiguration for Zinc Osmium Os Po element 114 3 Definitions Inner core electrons The electrons in the previous rare gas and any completed transition series d subshell Outer electrons All the electrons in the highest value of n Valence electrons All the outer electrons plus any electrons in any uncompleted transition series d subshell Converting between spdf and n l ml ms Write out the complete ground state electronic configuration for ruthenium Ru Complete the n l ml ms table for the valence electrons in ruthenium Give the orbital diagram for the valence electrons in ruthenium Identify the core electrons Identify the outer electrons Do the same thing for iodine 4 Exceptions to Predicted Electronic Configurations Several elements have ground state electronic configurations that are different than predicted by the periodic table Most of these exceptions occur in the f block elements You will not be responsible for these exceptions However there are five elements outside the f block elements that are exceptions and you will be responsible for these Lets look at these exceptions by considering the predicted ground state configuration for chromium Other exceptions Electronic Configurations for ions Anions are formed by adding the appropriate number of electrons to the configuration of the element This usually just means adding electrons to an already started sub level Most simple anions form by adding enough electrons to become iso electronic with the next rare gas Using rare gas cores give the electronic configurations for N3 Br1 5 Cations are formed by removing the appropriate number of valence electrons from the element However forming cations is more complicated than forming anions Electrons are first removed from the subshells having the highest value of n Consider Sr2 and Ni2 If more than one subshells have the same highest n value then the electrons are removed in reverse order to the way they filled Consider Sb3 Sb5 I f the subshells with the highest value of n do not contain enough electrons to make the desired cation then electrons are removed in reverse order from sub levels with the next highest value of n Consider Ni2 and Ni3 and Nb3 Another look at the Quantum Numbers 6 Element X rare gas core 9s2 6g18 7f 8d10 9p3 How many electrons have to be in the f level How many valence electrons How many unpaired electrons Name of first member of X s family Give the orbital diagram for the valence electrons Check list of terms Pauli exclusion principal paired electrons unpaired electrons energy shell energy subshell promoted electrons Hund s Rule valence electrons ground state atom excited state atom orbital both number of and shapes orbital diagrams valance electrons core electrons 7 Periodic Properties of the Elements Periodic Law When the elements are arranged by atomic numbers their chemical and physical properties vary periodically Topics we will discuss Effective nuclear charge nuclear screening Atom size radius Ion size radius Ionization energy Electron affinities Electronegativity General properties of metals and non metals Factors Affecting Electron Energies Nuclear charge Electron repulsions orbital shapes Remember attractions lower energy and repulsions raise the energy The higher the nuclear charge Z the greater the nucleus electron attraction and the more stable lower energy the system Once you have more than one electron in your system then electron electron repulsion enters the picture These repulsions act to raise the energy of the system Hunds Rule and the Compatability of Electrons 8 Remember what we have said about the stability of various possible electronic configurations in p d and f orbitals The following illustrates the correct order of stability for two electrons in p orbitals most stable least stable lower energy higher energy Effective Nuclear Charge In any multi electron atom there are two forces acting on all electrons The first force is the attractive forces of the positive nucleus for the negative electrons The second force is the repulsive forces between negatively charged electrons For the valence shell electrons this produces a situation where these electrons are being pulled inward by the nuclear charge and pushed outward by the electronelectron repulsions between the valence shell electrons and the core electrons The net result of this is that the effective nuclear charge Zeff felt by the valence shell electrons is diminished We say that the valence shell electrons have been shielded or screened from the full charge Zactual of the nucleus by the core electrons Zeff Zactual electron shielding by the core electrons Shielding Electrons Shielding electrons are the electrons in energy levels between the nucleus and the valence electrons They are called shielding electrons