Question

Compare and contrast the compounds CH4 and PH3 in terms of covalent bonding, molecular geometry (shape), and intermolecular forces. Which substance would experience a stronger attraction between its molecules, and why?

Answer 1

CH4 is polar while PH3 is non polar. I looked up the shape of PH3 because I wasn’t sure and I got “umbrella shaped”. I don’t know what it means by that because from a birds-eye-view that could be a circle but, from a view to the side it is roughly two perpendicular line (one of which curls at the end). CH4 is a teterahedral. And by intermolecular forces, the CH4 is London while PH3 is dipole-dipole. PH3 has stronger forces because it's a polar molecule

Answer 2

PH3 is isolectronic to ammonia (NH3), so they have the same shape, basically a squat three-sided pyramid, with the N or P at the apex.

Answer 3

And make it wiggle like crazy :-D That's basically the shape.

Answer 4

Be careful. CH4 (methane) is NON-POLAR due to its shape. The polarities of each C-H bond cancel out because it is a symmetrical molecule. The shape of PH3 is trigonal pyramidal, and although its shape might lead you to believe that it is polar, the reason that it is non-polar is because the electronegativity difference between each P-H bond falls within the non-polar range.

Answer 5

Nonsense. The PH3 molecule has a dipole moment of 0.6 D, which is quite respectable (about half that of the water molecule).

Answer 6

@Carl_Pham is correct. PH\(_3\) is also slightly soluble in water. (another tip off that it's polar)

But don't take my word for it: http://en.wikipedia.org/wiki/Phosphine