Page 80 - The Miracle in the Atom

THE MIRACLE IN THE ATOM

bond and it is incomprehensibly short-lived. The duration of a hydrogen
bond is approximately one hundred billionth of a second. But as soon as a
bond breaks, another one forms. Thus, water molecules adhere tightly to
each other while also retaining their liquid form because they are combined
with a weak bond.
Hydrogen bonds also enable water to resist temperature changes. Even
if air temperature increases suddenly, water temperature increases slowly
and, similarly, if air temperature falls suddenly, water temperature drops
slowly. Large temperature changes are needed to cause considerable chan-
ges in water temperature. The significantly high thermal energy of water has
major benefits for life. To give a simple example, there is a great amount of
water in our bodies. If water adapted to the sudden vicissitudes of tempera-
ture in the air at the same rate, we would suddenly develop fevers or freeze.
By the same token, water needs a huge thermal energy to evaporate.
Since water uses up a great deal of thermal energy while evaporating, its
temperature drops. To give an example, again from the human body, the
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normal temperature of the body is 36 C and the highest body temperature
we can tolerate is 42 C. This 6 C interval is indeed very small and even wor-
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king under the sun for a few hours can increase body temperature by that
amount. Yet, our bodies spend a great amount of thermal energy through
sweating, that is, by causing the water it contains to evaporate, which in turn
causes body temperature to drop. If our bodies did not have such an auto-
matic mechanism, working for even a few hours under the sun could be fa-
tal.
Hydrogen bonds equip water with yet another extraordinary property,
which is water's being more viscous in its liquid state than in its solid state.
As a matter of fact, most substances on earth are more viscous in their solid
states than in their liquid states. Contrary to other substances, however, wa-
ter expands as it freezes. This is because hydrogen bonds prevent water mo-
lecules from bonding to each other too tightly, and thus many gaps are left in
between them. Hydrogen bonds are broken down when water is in liquid
state, which causes oxygen atoms to come closer to each other and form a
more viscous structure.
This also causes ice to be lighter than water. Normally, if you melt any
metal and throw in it a few solid pieces of the same metal, these pieces wo-

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