Ionization Energy Lab Procedure:

Ionization Energy

Students

Part I: Ionization of a Metal

1. Create a spreadsheet that you can use to do your calculations. Title the first column 'Charge', the second column 'Ionization Energy', and the third column 'HOMO Energy'. In the 'charge' column list the numbers 0 through +3.
2. Next, select a metal element of your choice. Representative elements (not transition elements) work best. Be sure to pick an element that has a basis set.
3. Using the Waltz Interface for DISCO, create a run for the neutral atom of the metal you chose. First, enter a '1' into the periodic table under your element. (We are only looking at single atoms and ions, not molecules.) Also make sure that the calculation options are set to the defaults and 'Electron Density' is selected. Click continue.
4. For the neutral atom, the charge should equal zero. You may select the basis set of your choice. Consistency in basis sets is a suggestion.
5. When you have chosen your basis set, select 'DO DISCO'.
6. Waltz will then produce images of the atom or ion and create output files.
7. Open the 'Energy file' and copy the given value into your spreadsheet.
8. Also open the output file. Under the information for the iterations is a section called 'Eigenvectors and Orbital Energy'. Locate the HOMO and copy the HOMO energy value into your spreadsheet.
9. Repeat steps 3-7 for the first three ions of your element. Note that each ion has a different charge. When you prepare your run, remember to change the 'charge' box to +1, +2, or +3.
10. The energy values that you receive are given in hartrees (E_h. You will want to use your spreadsheet to convert these values into electron volts (eV). There are 27.216 eV/E_h.
11. Finally, graph the charge on the element against the ionization energy. Find the atom or ion with the minimum energy value. Observe how the energy changes as electrons are lost.

Part II: Ionization of a Non-Metal

Choose a non-metal and repeat Part I using a neutral atom, -1, -2, and -3 ions.

Part III: Subtraction vs. Koopman's Theory

For this section you will need your spreadsheet information, the ionization calculator, and your ionization energy literature values.

1. Open a new spreadsheet. Create three columns. Title the first column 'Ion', the second 'Subtraction Method' and the third 'Koopman's Theory'. Under the first column list your three ions.
2. Using the ionization calculator, fill in the values you recorded for the energy value of the ion, neutral atom, and HOMO energy as given in Hartrees. (The calculator automatically converts hartrees to eV and kJ/mol.
3. Next, enter your literature value for the correct ionization as given in kJ/mol and click 'Evaluate'.
4. The calculator should give you your converted units for both method. It also displays the percent errors for each method compared to the literature values. Record each of the two values in the appropriate column in your spreadsheet.
5. Repeat steps 2-4 for each of your ions.
6. Graph the ions vs. each of the two methods and determine which method is more accurate.
7. Repeat this section for your non-metal element.