7. The Aufbau Principle; Photoelectron Spectroscopy

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Session Overview

Modules Structure of the Atom
Concepts ionic bonding: octet stability by electron transfer, properties of ionic compounds, ionic lattice energy, and ionization energies, electron filling order, quantum numbers (n, l, m, s), photoelectron spectroscopy
Keywords Erwin Schrödinger, electron orbital, Aufbau principle, quantum numbers, wavefunction, eigenfunction, Schrödinger equation, simple harmonic oscillator, wave equation, atomic number, ionic separation, valence electrons, valence shell, average valence electron energy (AVEE), covalent bond, ionic bond, ionic compound, melting point, noble gases, valence shell occupancy, primary bond, metal, nonmetal, semimetal, metalloid
Chemical Substances magnesium (Mg)
Applications gas dynamics, crystals, electrometallurgy, applications of magnesium (Mg) – e.g. substitute for steel in automobiles


Before starting this session, you should be familiar with:

Looking Ahead

Prof. Sadoway discusses ionic crystals and the Born-Haber cycle (Session 8).

Learning Objectives

After completing this session, you should be able to:

  • Identify each term in the Schrödinger equation.
  • Describe the differences between covalent and ionic bonding.
  • Explain how ionic interactions influence ionic separations.
  • State the factors that contribute to the stability of ionic compounds.
  • Describe the general physical properties of ionic compounds.
  • Explain how interatomic bonding in ionic, molecular, and covalent solids influences their melting points.


Archived Lecture Notes #1 (PDF), Section 4

Book Chapters Topics
[Saylor] 6.6, "Building Up the Periodic Table." Electron spin: the fourth quantum number; the Pauli principle; electron configurations of the elements
[Saylor] 7.3, "Energetics of Ion Formation." Ionization energies; electron affinities; electronegativity

Lecture Video

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This resource may not render correctly in a screen reader.Lecture Slides (PDF - 1.1MB)

Lecture Summary

In this lecture, Prof. Sadoway discusses the following topics:

  • n+l rule for filling orbitals. Fill in ascending n.
    • 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s
  • Measurement of ionization energies
    • Peak height tells number of electrons in shell
    • Energy tells shell (n)
  • Average valence electron energy (AVEE)


Only textbook homework problems are available for this session.

Textbook Problems

[Saylor] Sections Conceptual Numerical
[Saylor] 8.1, "An Overview of Chemical Bonding." 1 none
[Saylor] 8.2, "Ionic Bonding." 5, 6 none
[Saylor] 8.3, "Lattice Energies in Ionic Solids." 2, 3, 4, 5, 8 none
[Saylor] 12.5, "Correlation Between Bonding and the Properties of Solids." 2, 4 none

For Further Study


Erwin Schrödinger - 1933 Nobel Prize in Physics


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