CHEMISTRY COMMUNITY

If we don't "memorize" atom's electronegativity, is there a way to intuitively know what makes a polar vs nonpolar molecule?

I assume there examples we will be given will have molecules with atoms of obviously different electronegativity, for example NH3 or H2O and we're not expected to know the exact electronegativity.

I remember Professor Lavelle saying in class we did not need to know exact the exact values of electronegativity, but as long as we have an idea of them we should be absolutely fine.

f electronegativity values are given, the difference in electronegativity values is 0.4 or greater, the bond is polar.

Usually molecules with lone pairs tend to be polar, ex: trigonal pyramidal has 1 lone pair and is polar, unless the vsepr shape is non-symmetrical and in that case the bond would be non polar despite the lone pairs, ex: square planar has 2 lone pairs and is non-polar because it is symmetrical

The farther two elements are on the periodic table, the more electronegativity difference between them.

I believe Professor said that we should just have an idea of electronegativity, but not necessarily the exact values. However a basic rule is the farther elements are from each other on the periodic table, the more the electronegative difference is.

I think it is important to know the general trend of electronegativity on the periodic table.

I feel like some of the homework problems can only be done when given the exact number for electronegativity. Will it be obvious on the test?