Final answer:
A molecule with a center of positive charge and a center of negative charge is said to have a dipole.
Step-by-step explanation:
A molecule that has a center of positive charge and a center of negative charge is said to have a dipole. A dipole is any molecule with an unequal distribution of electron density, resulting in a positive and negative end.
For example, in a molecule like hydrogen fluoride (HF), the fluorine atom is more electronegative than the hydrogen atom. This causes the electrons in the bond to be closer to the fluorine, resulting in a partial negative charge on the fluorine end and a partial positive charge on the hydrogen end.
Other examples of polar molecules include water (H2O) and ammonia (NH3), which also have centers of positive and negative charge due to the unequal distribution of electrons.