Periodic Trends


The objective of this exercise is to observe periodic trends in bond angles as we move around the period table.


Use the specified calculation method to fill in the bond angles of the following molecules:

Molecule PM3 Bond Angle Ab Initio [HF/6-311G+(d,p)] Experimental Bond Angle
H2O     104.5
H2S     92.3
H2Se     92.3
F2O     103.2
Cl2O     110.8

In the following section, you will use the WebMO editor to determine the atomic radius of several atoms. Using the WebMO editor, draw a dimer of each of the following atoms. Enter adjust mode and select both atoms; the bond distance should be displayed in the status bar. Dividing this bond length by two yields the atomic radius for that atom.

Atom O S Se H F Cl

Describe and explain the trends observed in bond angle as a function of

Central Atom:

Outer Atom:

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