1Week 5 CHEM 1310 - Sections L and M 1Quantum Mechanics Quantum Numbers– Pauli Exclusion Principle– Aufbau Principle– Hund’s Rule– Valence Electrons Periodic Table Trends– Ionization Energy– Electron Affinity– Atomic RadiiWeek 5 CHEM 1310 - Sections L and M 2Pauli Exclusion PrincipleIn an atom, no two e- can have the same set of quantum #’s. nlmlmsWeek 5 CHEM 1310 - Sections L and M 3Aufbau PrincipleElectrons add one by one to atomic orbitals to“build up” from lower to higher energy states.orbitalsEach orbital can hold 2 e-2Week 5 CHEM 1310 - Sections L and M 4Aufbau PrincipleElectrons add one by one to atomic orbitals to“build up” from lower to higher energy states.“s” subshell can hold only 2 e-“p” subshell can hold up to6 e-Only 2 e- in the 2p subshellWeek 5 CHEM 1310 - Sections L and M 5Hund’s Rule When several orbitals are of equal energy, a singlee- enters each orbital before a second e- enters.6C:1s2 2s2 2px1 2py1Week 5 CHEM 1310 - Sections L and M 6Hund’s RuleThe spin of electrons filling orbitals of thesame energy level remain parallel untilelectron pairs can be formed.7N:1s22s22px12py12pz18O:1s22s22px22py12pz13Week 5 CHEM 1310 - Sections L and M 7Trends in the Periodic TableWeek 5 CHEM 1310 - Sections L and M 8Valence Electrons Electrons in theoutermost (i.e. highestenergy) shell of an atom Directly involved inbonding Number of valence e- issame as the Group # inthe Periodic TableIncreasing # of valence e- across periodWeek 5 CHEM 1310 - Sections L and M 9Valence Electrons8O1s2 2s2 2px2 2py1 2pz11s2s2pE# of e- in the outer-most shell6Notice that 2 of oxygen’s valencee- are unpaired!4Week 5 CHEM 1310 - Sections L and M 10PRS QuestionWho developed the theory that no two electrons can have the same set of quantum numbers?(1) Hund(2) Aufbau(3) Heisenberg(4) Pauli(5) EinsteinWeek 5 CHEM 1310 - Sections L and M 11PRS QuestionWho developed the theory that no two electrons can have the same set of quantum numbers?(1) Hund(2) Aufbau(3) Heisenberg(4) Pauli(5) EinsteinPauli Exclusion PrincipleWeek 5 CHEM 1310 - Sections L and M 12PRS QuestionWhat is the maximum number of electrons that can occupythe orbitals with principle quantum number = 4?(1) 2(2) 8(3) 18(4) 32(5) None of the above5Week 5 CHEM 1310 - Sections L and M 13PRS QuestionWhat is the maximum number of electrons that can occupythe orbitals with principle quantum number = 4?(1) 2(2) 8(3) 18(4) 32(5) None of the above4s = 24p = 64d = 104f = 14Sum = 32Week 5 CHEM 1310 - Sections L and M 14PRS QuestionWhich of the following elements has 4 valence electrons?(1) Be(2) Si(3) P(4) Al(5) AsWeek 5 CHEM 1310 - Sections L and M 15PRS QuestionWhich of the following elements has 4 valence electrons?(1) Be - 2(2) Si(3) P - 5(4) Al - 3(5) As - 56Week 5 CHEM 1310 - Sections L and M 16PRS QuestionHow many valence electrons does Mg2+ have?(1) 0(2) 1(3) 2(4) 3(5) 12Week 5 CHEM 1310 - Sections L and M 17PRS QuestionHow many valence electrons does Mg2+ have?(1) 0(2) 1(3) 2(4) 3(5) 12Mg is in Group 2(meaning 2 valence e-) but Mg2+ has lostthem!Week 5 CHEM 1310 - Sections L and M 18Ionization EnergyIonization energy is that required to remove an e- from agaseous atom or ion in the ground state.7Week 5 CHEM 1310 - Sections L and M 19Atomic RadiusThe radius of an atom (r) is definedas half the distance between the nuclei in a moleculeconsisting of identical atoms.Week 5 CHEM 1310 - Sections L and M 20Comparing Atomic RadiiElements with very different # of e- can have similar atomic radii.13 e-88 e-Distance inpicometers1 x 10-12 mWeek 5 CHEM 1310 - Sections L and M 21Atomic radiusincreases downa groupAtomic radiusdecreasesacross a periodPeriodic Trends: Atomic Radiismallerlarger8Week 5 CHEM 1310 - Sections L and M 22Next WeekRecap of Chapter 12– Summary of what to learn re: Quantum Mechanics– More practice questions re: QMBegin Chapter 13: Bonding– Read entire