Answer to Question #229422 in Biochemistry for tash

Question

explain why water is considered to be a dipole molecule

Answer 1

Hydrogen and oxygen have different electronegativities. There is a partial negative charge on oxygen atom, and partial positive charge on each hydrogen atom of water. The central atom (oxygen) has 4 electron domains: two single bonds and two lone pairs, which determines the bent molecular geometry of water. In this type of geometry, two dipoles between oxygen and hydrogen cannot cancel out as they are not oppositely directed. This causes one "side" of the molecule to be slightly negatively charged while the other one bears a slightly positive charge. Therefore, the molecule is overall polar, and has a dipole moment. The simple illustration is attached below.