[confused26]

Can anyone give me a good strategy to choose the greater dipole moment between 2 molecules? 

Here are a few problems that I did
1. CH3NH2 or CH3OH - In circumstances where a central atom is surrounded by similar molecules and atoms in each case will we find that the one with the greater dipole moment is the more electronegative element?  So in this case oxygen is more electronegative than Nitrogen so it has a greater dipole moment?  Is this the reasoning you use?

2.In CHCl3 or CCl3F do we deduce that CHCl3 has the greater dipole because Cl and F are both more electronegative than C the positive and negative dipoles are located very close to each other making the dipole moment small whereas in CHCl3 the dipole positive is located around C and H and the dipole negative is located by the 3 Cls.

3.In (CH3)3CH or (CH3)3CCl the Cl is what causes (CH3)3CCl to have a greater dipole moment than (CH3)3CH?  The polarity is not strong between C and H compared to the polarity between C and Cl so this causes (CH3)3CCl to have a greater dipole moment?

Can anyone give me adequate explanations of where the greater dipole moment is found between the molecules and also a strategy to solve problems like the ones above?  Any input will be greatly appreciated.  Thank you.

[Chemistry Tutor]

Here is my general strategy:

Write a Lewis then structural formula for both molecules

Place dipole arrow on the molecule using the length of the arrow to represent the difference in EN over the bond between two atoms

Guesstimate any vectors cancellation or additions of the dipoles