are allowed for an orbital with n=2? 7.21 Electronic Spin Quantum Number • • Has values of • Electronic spectra show magnetic moment with two values • Leads to Pauli exclusion principle -no two electrons in an atom can have the same 4 quantum numbers 7.23 Question What are four quantum numbers one random e - in each subshell with a principal quantum number n=3?
Chapter 7 Quantum Mechanics 7.24 Nodes • Total number of nodes = • Angular nodes = • Radial nodes = 7.25 Orbital energy for a one electron atom • All orbitals with the same principal quantum number have • A larger n values means • Electrons in the have the lowest energy possible • The ground state for a one electron H atom is 7.25 Orbitals with more than one electron • In many e - systems energy depends on < < < • e - will go into the lowest energy orbitals first 7.26 Penetration • 2p has maximum probability • 2s has small but significant electronic probability • 2s to the nucleus more than 2p • 2s is than 2 p 1s 2s 3s 2p 3p
Chapter 7 Quantum Mechanics 2.27 Magnetic Properties • Diamagnetic – • Paramagnetic – 7.28 History of the Periodic Table • Elements grouped by properties • Mendeleev is given the most credit for the current version of the periodic table • Mendeleev was able to successfully predict properties of unknown elements 7.29 Periodic tables Main group (representative elements) Transition metals Lanthanides and Actinides 7.30 Electron configurations: • Hydrogen • Helium • Lithium • C • Mn • Mn 2+ 7.31 Aufbau Principle • e - s are added to hydrogen–like orbitals • Follow order of periodic table • Start with 7.32 Hund’s Rule • Lowest energy configuration for an atom 7.33 Valence and Core e - s • Valence e - s are in the shell with the outermost • Atoms with the same number of valence e - have • They are in the same for the main group elements • Core e - s are the inner e - s • Core e - s shield the valence electrons
Chapter 7 Quantum Mechanics 7.34 Periodic Trends • Two key conflicting properties 1) 2) 7.35 Effective nuclear charge • Z is the number of • Positive charge • Core electrons valence electrons • Z eff = • S is a scaling factor • No easy way to know S and therefore Z eff • Core charge can serve as an approximation • Core charge = 7.36 Ionization Energy • Energy required to $O²J± Æ Al + ²J± + e - I 1 ¶¸¹ kJ/mol Al + ²J± Æ Al 2+ ²J± + e - I 2 º¸º¶ kJ/mol Al 2+ ²J± Æ Al 3+
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- Fall '08