Question

How do you find Polarity?

Answer 1

Uneven dipole moments in an asymmetrical molecule...

Explanation:

Polarity happens when a molecule has a partially positive end and a partially negative end. This happens when the bond between atoms has a big electronegativity difference.

For example, in ammonia `(NH_3)`, the nitrogen has an electronegativity of `3.04`, while hydrogen has only an electronegativity of `2.2`. The difference `(DeltaEN=0.84)` is actually quite a lot, so hydrogens' electrons get pulled towards nitrogen's nucleus, leaving the hydrogens a positive charge on one end, while the lone unpaired electrons on the nitrogen form a negative charge on the other end.

Here is a picture:

As you can see here, the nitrogen pulls the hydrogens' electrons, which therefore leaves a positive charge on one end of the molecule (the hydrogens), and a negative charge on the other end (the lone electrons of nitrogen).