Water is a polar molecule and also acts as a polar solvent. When a chemical species is said to be “polar,” this means that the positive and negative electrical charges are unevenly distributed. The positive charge comes from the atomic nucleus, while the electrons supply the negative charge. It’s the movement of electrons that determines polarity. Here’s how it works for water. Water (H2O) is polar because of the bent shape of the molecule. The shape means most of the negative charge from the oxygen on side of the molecule and the positive charge of the hydrogen atoms is on the other side of the molecule. This is an example of polar covalent chemical bonding. When solutes are added to water, they may be affected by the charge distribution.