The repulsive effects of the two lone pairs on the oxygen atom cause water to have a bent, not linear, molecular structure, allowing it to be polar. The hydrogen–oxygen–hydrogen angle is 104.45°, which is less than the 109.47° for ideal sp hybridization. The valence bond theory explanation is that the oxygen atoms lone pairs are physically larger and therefore take up more space than the oxygen atoms bonds to the hydrogen atoms. The molecular orbital theory explanation (Bents rule) is that lowering the energy of the oxygen atoms nonbonding hybrid orbitals (by assigning them more s character and less p character) and correspondingly raising the energy of the oxygen atoms hybrid orbitals bonded to the hydrogen atoms (by assigning them more p character and less s character) has the net effect of lowering the energy of the occupied molecular orbitals because the energy of the oxygen atoms nonbonding hybrid orbitals contributes completely to the energy of the oxygen atoms lone pairs while the energy of the oxygen atoms other two hybrid orbitals contributes only partially to the energy of the bonding orbitals (the remainder of the contribution coming from the hydrogen atoms' 1s orbitals).