dingsbunnyranch said:How do you calculate the distances between atoms of a given gas molecule? The reason I am asking this is so I can find the moment of inertia of certain molecules so i can determine degrees of freedom for a gas at a certain temperature. Is there an easier way to determine them?
HallsofIvy said:Pythagorean, I think you misunderstood the question. The question was not about the distance between molecules (atoms) in a gas but about the distance between atoms in a single molecule.
I don't see any simple way to answer that- it depends on the type of gas. You might be able to look up distance between atoms for a particular molecule in something like the CRC tables.
This weak attraction takes place already at long distances of 100 nanometer, whereas the stronger repulsion only becomes preponderant at distances of 100 picometer, a distance which is similar to atomic radii. The atoms are held together at the distance at which the attractive and repulsive forces cancel out.
The length of a chemical bond is taken to be the average distance between the two nuclei. For gases it can be determined to a high degree of accuracy by rotational spectroscopy or by electron diffraction. For solids, it is usually measured by X-ray diffraction: however this method cannot measure the length of bonds involving hydrogen, for which neutron diffraction must be used. Average bond lengths (often with standard deviations) for a large number of bond situations in inorganic and organic compounds have been calculated from data in the Cambridge Crystallographic Database. Other factors being equal, a shorter bond is also a stronger bond.