Question

What does it mean if a molecule is polar?

Answer 1

When a molecule is polar, it means that it has positive and negative ends.

Explanation:

By definition, polarity is basically the status of having "poles."
In a molecule, this means that the molecule has poles of positive and negative charge—also known as a separation of charge.

Let's take a look at a classic example of polarity: the water molecule.

Oxygen is more electronegative than hydrogen.
This means that, in the `O–H` bond which is in `H_2O`, oxygen will attract the shared electrons better than hydrogen.
So, electrons in each `O–H` bond will spend more time with oxygen than with hydrogen.

Therefore, these `O–H` bonds are polar bonds—bonds where electrons spend more time with one atom, causing that one atom to have a more negative charge.

In `H_2O`, these polar bonds are also arranged in such a way that they create a separation of charge in the entire molecule:

• There is a center of negative charge at the top, where `O` is.
• There is a center of positive charge at the bottom, where `H` is.

This existence of a positive and negative pole causes the entire `H_2O` molecule to be polar.