Triatomic molecules carbon monoxide

There are numerous theoretical and experimental results demonstrating that simple molecular solids transform into nonmolecular phases at high pressures and temperatures, ranging from monatomic molecular solids such as sulfur [61], phosphorous [62] and carbon [63] to diatomic molecular solids such as nitrogen [8, 9,40], carbon monoxide [12] and iodine [20, 21], to triatomic molecules such as ice [24, 25], carbon dioxide [10, 31, 37] and carbon disulfide [64, 65] to polyatomics such as methane [27, 28] and cyanogen [11], and aromatic compounds [29]. In this section, we will limit our discussion within a few molecular triatomics first to review the transformations in two isoelectronic linear triatomics, carbon dioxide and nitrous dioxide, and then to discuss their periodic analogies to carbon disulfide and silicone dioxide. 

Radiation from clear gas does not follow the Stefan-Boltzmann fourth-power law. The only clear gases that emit or absorb radiation appreciably are those having three or more atoms per molecule (triatomic gases) such as CO2, H2O, and SO2. An exception is diatomic carbon monoxide (CO), which gives off less radiation. The other diatomic gases, such as O2, N2 (and their mixture, air), and H2 have only negligible radiating power. 

The three pure substances just mentioned iUustrate three types of molecules found in matter. Oxygen molecules consist of two oxygen atoms, and are called diatomic molecules to indicate that fact. Molecules such as oxygen that contain only one kind of atom are also called homoatomic molecules to indicate that the atoms are all of the same kind. Carbon monoxide molecules also contain two atoms and therefore are diatomic molecules. However, in this case the atoms are not identical, a fact indicated by the term heteroatomic molecule. Carbon dioxide molecules consist of three atoms that are not all identical, so carbon dioxide molecules are described by the terms triatomic and heteroatomic. The words diatomic and triatomic are commonly used to indicate two- or three-atom molecnles, bnt the word polyatomic is usually used to describe molecules that contain more than three atoms. 

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