Question

. List ALL of the intermolecular forces that are present in each element or compound. a. N2 b.PH3 c. NF3 d. XeF2

Answer 1

1.The N2 molecules are nonpolar , so only dispersion forces are present

2.P has 5 valence electrons, leaving a lonepair if it interact with only 3 H(s). The molecular geometry of PH3 is trigonal pyramid (AX3e1) which is polar.Dispersion forces and dipole-dipole forcesexist in this molecule Dipole-dipole force exist only in polar molecules

3.In NF3 molecule there are 3 single bonds and one lone pair on N atom. Because of VSEPR theory, the shape of the molecule is pyramidal. The N side of the molecule is slightly positive and Fs side is slightly negative. Therefore the molecule is polar. For polar molecules the predominant intermolecular force is the dipole-dipole attraction.

Although the molecule contains 2 of the three essential atoms (F, O, N) for H-bonding, since there is no H atom attached to N atom , H-bonding does not exist. If it were NHF2, the predominant intermolecular force would be H-bonding.

4.The dipole moments cancel because the molecule is linear, so XeF2 is nonpolar.XeF2 has dispersion attractions.