Geology Reference
In-Depth Information
Figure 18: A hydrogen atom with its lone electron.
Nitrogen encounters its most stable relationship with itself. It has a full inner orbit, but
misses three outer electrons. This means that two nitrogen atoms create a triple covalent
bond which requires a great deal of energy to break apart; two nitrogen atoms linked
in this way are like virtually inseparable twins, and nitrogen gas is thus highly unreact-
ive. In a process invented by the German chemist Haber, nitrogen gas is forced to react
with hydrogen to make ammonia, but this can only be done with a catalyst present and
at temperatures of 500
0
C and a pressure 1,000 times greater than normal atmospheric
pressure. Perhaps nitrogen suffers when it is forced to separate under these extreme con-
ditions; it may feel more comfortable when bacteria carry out this operation, for they
are the only life-forms that can bring about this extraordinary feat at everyday temper-
atures. Working in partnership with plants such as clovers and legumes, which house
the microbes in special root nodules, they split the nitrogen shielded from the ardent
and potentially destructive attentions of oxygen. It is essential that nitrogen does indeed
stay twinned as molecular nitrogen gas (N
2
), for, as the most abundant gas in the atmo-
sphere (78%), its collective weight at the Earth's surface produces the right pressure for
the greenhouse effect which regulates the Earth's temperature, although any extra nitro-
gen would asphyxiate oxygen-breathing life. Atmospheric nitrogen also dilutes oxygen,
which is thereby restrained from consuming anything in its path in spectacular global
combustion. Nitrogen is a nutrient essential to all life, and is of critical importance for
the formation of DNA, the haemoglobin in our blood and amino acids, which can link
up thanks to nitrogen, forming protein molecules of potentially vast size. Nitrogen is of
course also the basis of dynamite and TNT. These compounds are so famously explos-
ive because nitrogen will combine with itself at the slightest opportunity, releasing vast
amounts of energy in the process.
