Final answer:
A molecule with opposite electrical charges on each end is called a polar molecule, which forms due to an unequal sharing of electrons in polar covalent bonds. This leads to a dipole with partial positive and negative charges like in water molecules.
Step-by-step explanation:
When a molecule has an opposite electrical charge on each end, this is indicative of a polar molecule. In such molecules, the electron distribution is uneven, resulting in the formation of polar covalent bonds. For example, in the molecule water (H2O), the oxygen end has a partial negative charge (anionic), while the hydrogen end has a partial positive charge (cationic). This creates a dipole, much like a magnet with a north and a south pole.
Polar molecules, such as hydrogen fluoride (HF), have electrical charges on either end of the molecule that do not cancel each other out inside an insulator. The presence of these charged regions allows polar molecules to interact with each other, as seen in the attraction between the positive hydrogen end of one water molecule to the negative oxygen end of a nearby one, forming weak hydrogen bonds.
In addition, polar molecules orient themselves in an electric field with positive ends attracted to the negative plate, and negative ends attracted to the positive plate. This property of polar molecules is essential in many biological and chemical processes.