Slides10

Lecture #8

Text: Section 12.15

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Lecture Outline

The Periodic Table (continued)

Ionization energies

Second and third ionization energies

Electron affinity

The energy needed to remove the easiest-to-remove electron from a neutral atom is called the first ionization energy.

First ionization energies for light elements. Using this information, we can estimate the effective nuclear charge, Z_eff, for the electron being removed. Helium as an example.

Z_eff for lithium

Z_eff for neon

The detailed trend in ionization energies for the light elements

The n=1 shell filling

The n=2 shell filling after which the n=3 shell starts

Starting the p-subshell causes a break in the smooth trend across the row.

Starting to pair up electrons after half the p-subshell is filled causes a second break, which we referred to as the mid-shell dip, in the smooth trend across the row.

First ionization energies across rows 1 through 3 of the Periodic Table

Overlapping the 2nd and 3rd row element first ionization energies to demonstrate the repeating pattern (determined by valence electron configuration)

Second ionization energies

First, second, and third ionization energies for the light elements

First, second, and third ionization energies shifted to show, again, that valence electron configuration is the determining driver

Electron affinity is the energy involved in adding an electron to a neutral atom to form a negative ion. It is numerically equal to minus the ionization energy for that negative ion. As such, we should expect that the electron affinities also depend on electron configuration.