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Valence bonds

These last considerations can also be applied to explaining, qualitatively, why some particular atoms do bond. Consider, for example, the common molecule Carbon Dioxide, CO2, consisting of one Carbon atom and two Oxygen atoms. This is pictured below.

Figure 12.11: Carbon Dioxide
\epsfysize=4 cm

Only the electrons in the outer shell (n = 2) are shown.

From this figure, we see that if the atoms ``share'' their electrons in the manner indicated, then, at times, each atom will have a filled n = 2 shell with 8 electrons. This sharing of electrons between atoms can be viewed in light of the Heisenberg uncertainty relations, which says that it is impossible in principle to say where precisely an electron is located. Such a configuration is energetically favoured, as this molecule is less likely to interact with other atoms and is therefore more stable, and for this reason these valence bonds occur quite frequently in nature.