What is the molecular geometry of H2O?

The molecular geometry of water (H2O) is described as bent due to the arrangement of its electron pairs around the central oxygen atom. Water has two hydrogen atoms bonded to oxygen and two lone pairs of electrons on the oxygen. According to the VSEPR (Valence Shell Electron Pair Repulsion) theory, the presence of these lone pairs leads to a repulsion that causes the bonded hydrogen atoms to form an angle of approximately 104.5 degrees, rather than extending in a straight line. This results in a bent or angular geometry instead of being linear.

The tetrahedral angle of 109.5 degrees could be mistakenly considered due to the four regions of electron density (two bonds and two lone pairs), but the molecular geometry specifically describes the physical shape formed by the atoms themselves, excluding the lone pairs. In this case, the geometry is deemed bent because the lone pairs are not visible as part of the molecular shape.

While linear geometry could apply to molecules with only two atoms, it doesn't account for the presence of lone pairs, which distort the arrangement. The tetrahedral and trigonal planar options refer to shapes formed with different configurations of bonding and lone pairs that are not applicable to water. In conclusion, water's unique bent geometry arises from