Chemistry · Ch 9 — Hydrogen
Structure of Water
Structure of Water
Molecular Geometry
In the gas phase, a single water molecule is bent, not linear, with a bond angle of 104.5° and an O–H bond length of 95.7 pm (Fig 9.1a). This bent shape makes water a highly polar molecule (Fig 9.1b): oxygen, being more electronegative, pulls electron density toward itself, leaving oxygen with a partial negative charge () and each hydrogen with a partial positive charge ().
Bonding picture: the orbital-overlap diagram (Fig 9.1c) shows oxygen using roughly -hybridised orbitals — two of these overlap with hydrogen 1s orbitals to form the two O–H sigma bonds, while the remaining two hybrid orbitals hold oxygen's two lone pairs.
In the liquid phase, individual water molecules associate with their neighbours through hydrogen bonds, the root cause of many of water's unusual bulk properties (see 9.6.1). …
What this figure shows. Three-panel line diagram labelled 'H2O molecule' beneath. Panel (a): a bent triatomic molecule drawn as 'O' at the apex with two lines going down to 'H' on the left and 'H' on the right; the bond angle at O is marked '104.5°' and one O-H bond is labelled '95.7 pm'; captioned '(a)' below. Panel (b): the same bent V-shape, now with '2δ−' marked above the O atom and 'δ+' marked above each H atom, showing the molecule as a permanent dipole with the negative end at O and positive ends at the two H atoms; captioned '(b)' below. Panel (c): an orbital-overlap picture — a cluster of blue balloon/petal-shaped lobes (representing sp3-like hybrid orbitals on oxygen) radiating from a central point, with two of the lobes each ending in a small sphere labelled 'H' (one lower-left, one lower-right), representing the two O-H sigma bonds formed from two of the lobes while the other two lobes (pointing up) represent the two lone pairs on …