The Structure of Typical Homopolar Molecules

The remaining molecules in our list are NO, 02, N2, CO, HC1, and HBr. The first of these, NO, is the most peculiar compound in the list and one of the most peculiar of the known compounds. We note that nitrogen supplies five, and oxygen six, outer electrons to the compound, making a total of eleven, an odd number. It is quite obvious that an odd number of electrons cannot form closed shells, electron pairs, or anything else associated with stable molecules. As a matter of fact, out of all the enormous number of known chemical compounds, only a handful have an odd number of electrons, and NO is almost the only well-known one of these. We shall make no effort to explain it in terms of ordinary valence theory, for it is in every way an exception, though it can be understood in terms of atomic theory. 

1 See Sponer, Molekiilspektren und ihre Anwendungen auf chemische Probleme, Vol. I, Springer, 1935, for interatomic distances of diatomic and polyatomic molecules in this chapter. 

We have already discussed the structure of the next two molecules, HC1 and HBr, whose valence properties are indicated by the symbols 

There are only a few other common inorganic molecules to be mentioned. CO2 is a linear structure, with valences symbolized by 

The distance between end atoms is 2.38 A, slightly greater than the value 2 X 1.16 = 2.32 A between end atoms in COj. Here again we see the resemblance between Nj and CO, in that they form similar molecules when another oxygen atom is added. The molecule SO is a triangular molecule shaped something like water. Its structure presumably is 

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