Water’s polarity causes the molecules to loosely stick to one an-
other, a phenomenon called hydrogen bonding—the slightly negative
oxygen atom of one water molecule is attracted to the slightly positive
hydrogen atom of another. (Opposite electric charges are attracted
to one another.) This results in a matrix of water molecules held
together in a loose way by hydrogen bonds, depicted here as dashed
lines.
Hag “ Oo : ; ,
H “O° “@
H Hi... WH. H
Ho” O 1@)
Hy.” oO | |
“O | AH H
H Hi
JH |
Hs 9’ H
|
H
Water, with hydrogen bondsHydrogen bonding is noncovalent—it does not involve sharing of
electrons. The water molecules are able to easily slip and slide past
one another, producing the wateriness of liquid water. When water is
heated the energy of the heat causes the molecules to jitter and shake
more vigorously. At the boiling point, the jittering becomes vigorous
enough to overcome the hydrogen bonding between water molecules,
and the HO molecules escape as gaseous water—steam. Cool the
water, and the molecular vibration lessens until, at the freezing point,
the water molecules lock into a rigid matrix interconnected by hydro-
gen bonds—ice. The slight expansion of water when it freezes is due