Geology Reference
In-Depth Information
Figure 17: Mutual fulfilment for carbon and oxygen atoms in the covalent bonds in the carbon
dioxide molecule.
Hydrogen
(Figure 18)
is the most abundant atom in the universe: 88% of all atoms are
hydrogen, and indeed hydrogen is the primordial atom from which all others are derived
through fusion in the intense heat and pressure within stars and supernovae explosions.
It the simplest and lightest of all atoms: in its most basic form it has just one proton in its
nucleus, which gives it its gravity-defying lightness, and one electron in its single orbit.
Hydrogen ions are the most chemically reactive ions in existence, and also the smallest.
Hydrogen seeks fulfilment by finding another electron for its single orbit, which holds
only two. This means that two hydrogen atoms happily bond to each other covalently
to make H
2
—a hydrogen molecule—but hydrogen also bonds cheerfully with other ele-
mental beings such as carbon, phosphorus or oxygen, and is a major constituent of living
beings. Hydrogen is an airy, flippant creature which would love nothing better than to
escape our planet altogether and return to its ancestral domain in outer space as hydro-
gen gas, for Gaia's gravitational field is not strong enough to keep it from floating off
into the vastness of the cosmos. If this were to happen, we would lose all our water and
the planet would dry out completely. This may well be what happened on Venus, but
life on our planet has various ways of recapturing free hydrogen by combining it with
oxygen before it can escape.
