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Chemistry LibreTexts

Unit 2: Periodic Properties of the Elements

  • Page ID
    36088
  • In this unit, we will explain how the arrangement of electrons in an atom enables chemists to predict and explain the chemistry of an element. As you study the material presented in this chapter, you will discover how the shape of the periodic table reflects the distribution of electrons within atoms.

    The elements in the periodic table are arranged in order of increasing atomic number. All of these elements display several other trends and we can use the periodic law and table formation to predict their chemical, physical, and atomic properties. Understanding these trends is done by analyzing the elements electron configuration; all elements prefer an octet formation and will gain or lose electrons to form that stable configuration.

    The learning objectives of this unit are:

    Unit Topic Learning Objectives

    2

    Atomic Orbitals

    1. Define degenerate
    2. Sketch an energy-level diagram for a multi-electron atom
    3. Predict the energy ordering of atomic orbitals based on their quantum numbers

    2

    Electron Spin Quantum Number

    1. Explain the importance of the electron spin quantum number
    2. State the restrictions on the electron spin quantum number
    3. List all the quantum numbers for each electron within an atom

    2

    Electron Configurations and Orbital Diagrams

    1. Represent the distribution of electrons in an atom using an electron configuration and an orbital diagram
    2. Explain the uses and difference between an electron configuration and an orbital diagram
    3. State and use Pauli’s Exclusion Principle
    4. Differentiate between core and valence electrons

    2

    Shielding and Penetration Effects

    1. Explain the phenomenon of electron shielding
    2. Explain how electron shielding results in energy levels that depend on n and l
    3. Explain the importance of orbital penetration
    4. Predict the relative degrees of penetration for various orbitals

    2

    Hund’s Rule and the Aufbau Principle

    1. State Hund’s Rule and the Aufbau Principle
    2. Use Pauli's Exclusion Principle, Hund’s Rule and the Aufbau Principle to predict the electron configurations of all elements
    3. Use the Noble Gas shorthand for electron configurations

    2

    Electron Configurations of Transition Metals

    1. Explain how the periodic table’s organization reflects the rules for quantum numbers
    2. Explain why there are exceptions to the electron configuration rules

    2

    Slater’s Rules

    1. Use Slater’s rules to predict the shielding constant experienced by an electron in a s-or p- orbital of an atom
    2. Use Slater’s rules to predict the shielding constant experienced by an electron in a d-or f- orbital of an atom

    2

    1. Applying Slater’s Rules
    2. The f-block
    1. Use shielding constants to explain experimental electron configurations
    2. Classify members of the f-block as lanthanoids or actinoids

    2

    1. Magnetism
    2. Electron Configurations of Ions
    1. Explain the difference between paramagnetism and diamagnetism
    2. Predict the magnetic property of an element based on its electron configuration and orbital diagram
    3. Determine the electron configuration of ions

    2

    The Periodic Table

    1. Describe the basic principles behind the layout of the periodic table
    2. Classify the elements into categories based on electron configurations

    2

    Periodic Trends: Atomic Radius

    1. Assign an element to a group label based on its electron configuration
    2. Calculate the effective nuclear charge of an atom, and explain how it is related to the concept of electron shielding
    3. Predict the trend in atomic radius along a row or down a column of the periodic table

    2

    Periodic Trends:

    Exceptions to Atomic Radii

    Ionic Radii

    1. Identify and explain exceptions to the periodic trends in atomic radii
    2. Predict the trends in ionic radius
    3. Identify isoelectronic atoms and ions

    2

    Periodic Trends:

    Ionization Energy

    Electron Affinity

    1. Define ionization energy
    2. Describe the trends in ionization energy of atoms
    3. Describe the trends in successive ionization energies
    4. Define electron affinity
    5. Explain the large differences in electron affinities between groups

    2

    Periodic Trends:

    Electronegativity

    Metallic Characteristics

    1. Explain the differences between ionization energy, electron affinity, and electronegativity
    2. Describe the trends in electronegativity
    3. Describe the trends in metallic characteristics