BH₃ and PH₃ each contain four atoms, with the three hydrogens surrounding the central atom. Do the two molecules have the same electron-group geometry? Do they have the same molecular shape? Name the geometry and the shape for both molecules. You know from Problem 6.59 that PH₃ is nonpolar. What about BH₃? Is it polar or nonpolar? Explain.

Data from Problem 6-59

Consider the PX₃ molecule, where X is either H or F.

(a) For X = H, the entire molecule is nonpolar. Why is this so?

(b) For X = F, the entire molecule is polar. Draw two molecules next to one another in proper orientation so as to yield a dipolar intermolecular attraction, and explain why the attraction occurs.