Predict the molecular structure (including bond angles) for each of the following. a. PCl3
b. SCl2
c. SiF4

PCl3 - trigonal pyramidal <109 degrees

SCl2 - bent<109 degrees

SiF4 - tetrahedral 109 degrees

Explanation:

The shape of all three molecules derive from a tetrahedral arrangement of electron pairs.

However, in PCl3 there is a lone pair of electrons on P and three bond pairs. This leads to the observance of a trigonal pyramidal geometry with bond angle <109 degrees.

In SCl2, there are four regions of electron density around S, two lone pairs and two bond pairs leading to a bent molecular geometry with bond angle <109 degrees.

In SiF4, there are four bond pairs and no lone pair. The molecular geometry is tetrahedral with a bond angle of 109 degrees.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.