Electron Configuration

And Periodic Properties

Atomic Radii

  • atomic radius- one-half the distances between nuclei of identical atoms that are bonded together.

  • Period Trends

    • The trends to smaller atoms across a period is caused by the increasing positive charge of the nucleus.

  • Group Trends

    • In general, the atomic radii of the main-group elements increase down a group

Ionization Energy

  • A+ + e- (A+ = ion with a single positive charge)

  • ionization- any process that results in the formation of an ion

  • Ionization energy (IE)- the energy required to remove one electron from a neutral atom of an element

  • Period Trends

    • Ionization energies of the main-group elements increase across each period

  • Group Trends

    • Among the main-group elements, ionization energy generally decrease down the groups

  • Removing Electrons from Positive Ions

    • Each successive electron removed from an ion feels an increasingly stronger effective nuclear charge (the nuclear charge minus the electron shielding)

Electron Affinity

  • Electron affinity - energy change that occurs when an electron is acquired by a neutral atom

  • A + e- ⇒ A- +energy

  • A + e- + energy ⇒ A-

  • Period Trends

    • As electrons add to the same p sublevel of atoms with increasing nuclear charge, electron

      • exception - between Groups 14&15

  • Group Trends

    • electrons add with greater difficulty down a group

  • Adding Electrons to Negative Ions

    • second electron affinities are all positive

Ionic Radii

  • cation - positive ion

  • anion - negative ion

  • Period Trends

    • left (cations) ⇒ right (anions)

  • Group Trends

    • Gradual increase of atomic radii down a group

Valence Electron

valence electrons - electrons available to be lost, gained, or shared in the formation of chemical compounds


  • Electronegativity - measure of the ability of an atom in a chemical compound to attract electrons from another atom in the compound

    • Linus Pauling

  • Period Trends

    • Electronegativities tend to increase across each period, although there are exceptions

    • Electronegativities tend to either decrease down a group or remain about the same

Periodic Properties of the d- and f-block elements

  • Atomic Radii

    • As the number of electrons in the d sublevel increase, the radii increase because of repulsion among the electrons

  • Ionization Energy

    • Ionization energies of the d-block and f-block elements generally increase across the periods

  • Ion Formation and Ionic Radii

    • Electrons in the highest occupied sublevel are always removed first

  • Electronegativity

    • The general trend for electronegativity values to increase as radii decrease

Brandi Hageman & Kaitlyn Imoehl

Works Cited

"Chemistry: Comparing Ionic Radii of Cs+ and Cl- Ions." Sciencefourms.net.

Sciencefourms.net, 2013. Web. 25 Oct. 2013.

Davis, R., Frey, R., Sarquis, M., & Sarquis, J. (2009). Modern chemistry. Orlando, FL: Holt, Rinehart, and Winsten.

"Electron Affinity Trends." Grandinetti Laboratory. Drupal, n.d. Web. 25 Oct. 2013.

"Elements, Atomic Radii and the Periodic Table." Crystal Maker Software. Crystal Maker, 2013. Web. 25 Oct. 2013.

"Periodic Trends." Chemwiki. University of California, n.d. Web. 25 Oct. 2013.

"Valence Electrons Periodic Table." TutorVista.com. NCS Pearson, 2013. Web. 25 Oct. 2013.

"What Is “Electronegativity” ?" LifeSun. Mantra&WordPress, n.d. Web. 25 Oct. 2013.