About Water Ionization
Water, The chemistry of life.
Whenever we attempt to determine whether there is life as we
know it on Mars or other planets, scientists first seek to
establish whether or not water is present. Why? Because life on
earth totally depends on water.
A High percentage of living things, both plant and animal
are found in water. All life on earth is thought to have arisen
from water. The bodies of all living organisms are composed
largely of water. About 70 to 90 percent of all organic matter
is water.
The chemical reactions in all plants and animals that
support life take place in a water medium. Water not only
provides the medium to make these life sustaining reactions
possible, but water itself is often an important reactant or
product of these reactions. In short, the chemistry of life is
water chemistry.
Water, the universal solvent
Water is a universal, superb solvent due to the marked polarity
of the water molecule and its tendency to form hydrogen bonds
with other molecules. One water molecule, expressed with the
chemical symbol H2O, consists of 2 hydrogen atoms and 1 oxygen
atom.
Standing alone, the hydrogen atom contains
one positive proton at its core with one negative electron
revolving around it in a three-dimensional shell. Oxygen,
on the other hand, contains 8 protons in its nucleus with
8 electrons revolving around it.
This is often shown in chemical notation as the letter O
surrounded by eight dots representing 4 sets of paired
electrons.
The single hydrogen electron and the 8 electrons of oxygen
are the key to the chemistry of life because this is where
hydrogen and oxygen atoms combine to form a water molecule, or
split to form ions.
Hydrogen tends to ionize by losing its single electron and
form single H+ ions, which are simply isolated protons since
the hydrogen atom contains no neutrons. A hydrogen bond occurs
when the electron of a single hydrogen atom is shared with
another electronegative atom such as oxygen that lacks an
electron.
Polarity of water molecules
In a water molecule, two hydrogen atoms are covalently bonded
to the oxygen atom. But because the oxygen atom is larger than
the hydrogen's, its attraction for the hydrogen's electrons is
correspondingly greater so the electrons are drawn closer into
the shell of the larger oxygen atom and away from the hydrogen
shells. This means that although the water molecule as a whole
is stable, the greater mass of the oxygen nucleus tends to draw
in all the electrons in the molecule including the shared
hydrogen electrons giving the oxygen portion of the molecule a
slight electronegative charge.
The shells of the hydrogen atoms, because their electrons
are closer to the oxygen, take on a small electropositive
charge. This means water molecules have a tendency to form weak
bonds with water molecules because the oxygen end of the
molecule is negative and the hydrogen ends are positive.
A hydrogen atom, while remaining covalently bonded to the
oxygen of its own molecule, can form a weak bond with the
oxygen of another molecule. Similarly, the oxygen end of a
molecule can form a weak attachment with the hydrogen ends of
other molecules. Because water molecules have this polarity,
water is a continuous chemical entity.
These weak bonds play a crucial role in stabilizing the
shape of many of the large molecules found in living matter.
Because these bonds are weak, they are readily broken and
re-formed during normal physiological reactions. The
disassembly and re-arrangement of such weak bonds is in essence
the chemistry of life.
To illustrate water's ability to break down
other substances, consider the simple example of putting a
small amount of table salt in a glass of tap water. With
dry salt (NaCl) the attraction between the electropositive
sodium (Na+) and electronegative chlorine (Cl-) atoms of
salt is very strong until it is placed in water.
After salt is placed in water, the attraction of the
electronegative oxygen of the water molecule for the positively
charged sodium ions, and the similar attraction of the
electropositive hydrogen ends of the water molecule for the
negatively charged chloride ions, are greater than the mutual
attraction between the outnumbered Na+ and Cl- ions. In water
the ionic bonds of the sodium chloride molecule are broken
easily because of the competitive action of the numerous water
molecules.
As we can see from this simple example, even the delicate
configuration of individual water molecules enables them to
break relatively stronger bonds by converging on them. This is
why we call water the universal solvent. It is a natural
solution that breaks the bonds of larger, more complex
molecules. This is the chemistry of life on earth, in water and
on land.

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