Unit II - Lecture 8ChemistryThe Molecular Nature of Matter and ChangeFifth EditionMartin S. SilberbergCopyright ! The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Electron Configuration and Chemical Periodicity8.1 Development of the Periodic Table8.2 Characteristics of Many-Electron Atoms8.3 The Quantum-Mechanical Model and the Periodic TableMendeleev’s Predicted Properties of Germanium (“eka Silicon”) and Its Actual PropertiesTable 8.1PropertyPredicted Properties of eka Silicon (E)Actual Properties of Germanium (Ge)atomic massappearancedensitymolar volumespecific heat capacityoxide formulaoxide densitysulfide formula and solubilitychloride formula (boiling point)chloride densityelement preparation72 amugray metal5.5 g/cm313 cm3/mol0.31 J/g*KEO24.7 g/cm3ES2; insoluble in H2O; soluble in aqueous (NH4)2SECl4 (<100oC)1.9 g/cm3reduction of K2EF6 with sodium72.61 amugray metal5.32 g/cm313.65 cm3/mol0.32 J/g*KGeO24.23 g/cm3GeS2; insoluble in H2O; soluble in aqueous (NH4)2SGeCl4 (84oC)1.844 g/cm3reduction of K2GeF6 with sodiumFigure 8.1Observing the effect of electron spin.Table 8.2 Summary of Quantum Numbers of Electrons in AtomsName Symbol Permitted Values Propertyprincipal npositive integers(1, 2, 3, …) orbital energy (size)angular momentumlintegers from 0 to n-1 orbital shape (The l values 0, 1, 2, and 3 correspond to s, p, d, and f orbitals, respectively.)magneticmlintegers from -l to 0 to +l orbital orientationspinms+1/2 or -1/2 direction of e- spinFigure 8.2 Spectral evidence of energy-level splitting in many-electron atoms.Factors Affecting Atomic Orbital EnergiesAdditional electron in the same orbitalAn additional electron raises the orbital energy through electron-electron repulsions.Additional electrons in inner orbitalsInner electrons shield outer electrons more effectively than do electrons in the same sublevel.Higher nuclear charge lowers orbital energy (stabilizes the system) by increasing nucleus-electron attractions.The Effect of Nuclear Charge (Zeffective)The Effect of Electron Repulsions (Shielding)Figure 8.3 The effect of nuclear charge on orbital energy.Figure 8.4 Shielding and orbital energy.Figure 8.5Penetration and orbital energy.Illustrating Orbital OccupanciesThe electron configurationn l#of electrons in the sublevelas s, p, d, fThe orbital diagram (box or circle)Figure 8.6Order for filling energy sublevels with electrons.Figure 8.7A vertical orbital diagram for the Li ground state.Sample Problem 8.1Determining Quantum Numbers from Orbital DiagramsPLAN:SOLUTION:Use the orbital diagram to find the third and eighth electrons.PROBLEM: Write a set of quantum numbers for the third electron and a set for the eighth electron of the F atom.9F1s 2s 2pThe third electron is in the 2s orbital. Its quantum numbers are:n = l = ml = ms= 2 0 0 +1/2The eighth electron is in a 2p orbital. Its quantum numbers are:2n = l = ml = ms= -1, 0, or +11 -1/2Figure 8.8Orbital occupancy for the first 10 elements, H through Ne.Figure 8.9 Condensed ground-state electron configurations in the first three periods.Figure 8.10Similar reactivities within a group.Figure 8.11A periodic table of partial ground-state electron configurations.Figure 8.12 The relation between orbital filling and the periodic table.Figure 8.13 Aid to memorizing sublevel filling order.Sample Problem 8.2 Determining Electron ConfigurationsPLAN:SOLUTION:PROBLEM: Using the periodic table on the inside cover of the text (not Figure 8.11 or Table 8.4), give the full and condensed electron configurations, partial orbital diagrams showing valence electrons, and number of inner electrons for the following elements:(a) potassium (K; Z = 19) (b) molybdenum (Mo; Z = 42) (c) lead (Pb; Z = 82)Use the atomic number for the number of electrons and the periodic table for the order of filling for electron orbitals. Condensed configurations consist of the preceding noble gas and outer electrons.(a) for K: (Z = 19)1s22s22p63s23p64s1[Ar] 4s1 4s1condensed configurationpartial orbital diagramfull configurationThere are 18 inner electrons.3d 4pSample Problem 8.2(b) for Mo: (Z = 42)1s22s22p63s23p64s23d104p65s24d4[Kr] 5s14d5 (c) for Pb: (Z = 82)[Xe] 6s24f145d106p2 condensed configurationpartial orbital diagramfull configuration5s 4dcondensed configurationpartial orbital diagramfull configuration1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p2There are 36 inner electrons and 6 valence electrons.6s 6pThere are 78 inner electrons and 4 valence electrons.5pDetermining Electron