Exercise 4.2

The attractive (London) forces that contribute to the van der Waals potential energy increase rapidly with the number of polarizable electrons.

Confirm this statement by constructing potential energy curves for the remaining noble gas pairs for which you have been given data (Ne......Ne, Ar......Ar, Kr......Kr and Xe......Xe).

In each case find the equilibrium separation and hence find the bond energy for the pair. Are any of these van der Waals interactions comparable in strength to the covalent bond in H2 ?

In order to calculate the equilibrium distance and energy, you must be able to clearly read the minimum from your graph. Experiment with the range of R over which you plot the graph to achieve this.

Notes:

Be careful when labelling the graphs to use the correct units.

Write your answers in your notebook.

Print out a hard copy of the final graph (with labelled axes and title) that you use to answer the questions in this exercise (Printing the graph is achieved by clicking with the right mouse button in the graph window, and selecting the option "Print", and then subsequently clicking OK twice).

If you need help you can page back through the notes.

When you have finished this exercise, go to the next page.



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