polar molecule

A polar molecule is a molecule in which one end of the molecule has a slightly positive charge, while the other end has a slightly negative charge.

• Most polar molecules have an asymmetric or uneven distribution of electrons.

• Polar molecules dissolve in polar molecules only.

H2O has one very electronegative oxygen that is always trying to keep the electrons closer to it than to the hydrogens it is bonded to. This actually gives the oxygen a slightly negative charge---because of the electrons that are spending more time next to it---and it gives the hydrogens a slightly positive charge.