Caption：(a) The space-filling structure of a water molecule shows oxygen as red and the two hydrogen atoms in white. (b) The electron configuration of a water molecule is tetrahedral, while the molecular structure is "bent" to yield a 104.5 degree angle between the hydrogen atoms. These hydrogen atoms have a partial positive charge. Oxygen also has 2 unbonded pairs of electrons that participate in hydrogen bonds because of their partial negative charges.
Notes：The sp3 hybrid orbital structure of oxygen in water leads to the formation of 4 hydrogen bonds by water.