Monoatomic molecules

Iodine vapor is characterized by the familiar violet color and by its unusually high specific gravity, approximately nine times that of air. The vapor is made up of diatomic molecules at low temperatures at moderately elevated temperatures, dissociation becomes appreciable. The concentration of monoatomic molecules, for example, is 1.4% at 600°C and 101.3 kPa (1 atm) total pressure. Iodine is fluorescent at low pressures and rotates the plane of polarized light when placed in a magnetic field. It is also thermoluminescent, emitting visible light when heated at 500°C or higher. 

The relative density of potassium vapour at 1040° (H unity) is between 40 and 45 very nearly corresponding with monoatomic molecules.59 The vapour densities of the alkali metals are somewhat inaccurate because they attack the containing vessels. The value for sodium, between 15 1 and 25 8, also agrees with a monatomic mol. W. Ramsay s experiments on the effect of potassium on the f.p. of mercury show that the alkali metals are possibly univalent in mercurial soln. C. T. Heycock obtained similar results from the effects of lithium, and potassium on the f.p. of sodium and of sodium on the f.p. of cadmium, tin, lead, and bismuth. 

The entropy of poly atomic molecules is more than that of a monoatomic molecule. 

The 14 possible Bravais lattices for crystals of a monoatomic molecule. The full designation shown here bears a numerical prefix—for example, 23Ffor face-centered cubic. When space groups are generated from the Bravais lattices, then this numerical prefix is dropped (e.g., the 23P cubic Bravais lattice reappears simply as P), because the other numbers or letters that follow the P will identify the space group uniquely. 

V, total number of monoatomic molecules (ions) in the Bravais cell. 

For case above it holds for the rates of elementary reactions (in a similar way as for monoatomic molecules) that the rates of elementary reactions can be described as... 

When the ideal gas is dissolved into a solvent at constant pressure, the solvent volume increases by nrksT. This volume increase, which has nothing to do with the molecular interactions, originates from the physical cause that the ideal gas makes the solvent volume increase in order to gain the entropy (at a constant pressure). The original K-B theory naturally includes this contribution in the form nTkB,T. This is true for solutes of monoatomic molecules. However, it is not so obvious if it applies to polyatomic solutes as well. If atoms in the solute molecule could move freely in the solvent, the ideal contribution would be N... 

The equation (23) is derived for dilute gases consisting of non-polar, spherical, monoatomic molecules. 

All noble gases are monoatomic molecules and chemically inert. Give reasons. 

The functions are called molecular orbitals. Obviously the discussion applies to the case of one atom (which may be considered to be a monoatomic molecule), and then the atomic orbitals. The relation (6) shows that the energy associated with a given state of the independent-electron model is the sum of the energies e, associated with the various orbitals introduced in the wave function 0°. 

There is no rotational term to consider for monoatomic molecules since the rotation about an axis passing through the nucleus, where practically the whole mass is concentrated, does not involve any etrergy. We will now consider three cases of polyatomic molecirles. 

If we sum the three contributions to calculate the value for the heat capacity at constant volume, as the characteristic temperatures of rotation are often lower than the Einstein temperature (see Table 7.3), the variation in the heat capacity, for example of a diatomic molecule, with temperature takes the form of the curve in Figure 7.12(c). At low temperatures, the only contribution is that of translation, given by 3R/2. Then if the temperature increases, the contribution of rotation, is added according to the curve in Figure 7.12(a) until the limiting value of this contribution is reached, then the vibrational contribution is involved until the molecule dissociates which makes the heat capacity become double that of the translational contribution of monoatomic molecules. The limiting value of the vibrational contribution is sometimes never reached. This explains why the values calculated in Table 7.2 are too low if we do not take into account the vibration and too high in the opposite case. 

This interpretation was made for diatomic molecules, and unlike with monoatomic molecules the behavior depends on other parameters. 

We have seen (cf. Ch. II, 4) that the properties of monoatomic molecules such as rare gases can be described to a fair degree of approximation by the Lennard-Jones (6-12) potential... 

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