Boiling points of the noble gases

Self-Test 5.2A Account for the trend in boiling points of the noble gases, which increase from helium to xenon. 

We will consider first a relatively simple case where the interactions between molecules are all of the same type (nonpolar molecules interacting as a result of London forces). For a liquid, the boiling point gives a measure of the strength of the forces between molecules in the liquid state because those forces must be overcome in order for the molecules to escape as a vapor. Figure 6.6 shows the boiling points of the noble gases and a few other substances as a function of the van der Waals a parameter. 

Let us consider as y the boiling points of the noble gases and then use the atomic number as the predictor x. This set of data is monotonic increasing, but without a clear... 

Why do the boiling points of the noble gases increase as the period increases ... 

Explain the order of increasing melting and boiling points of the noble gases in terms of polarizabilities of the atoms and forces of attraction between them. 

The predominant forces that exist between molecules of noble gases are dispersion forces because noble gas molecules are nonpolar. Dispersion forces increase with increasing mass of the particles involved, so the boiling points of the noble gases would increase in the order of He, Ne, Ar, Kr, Xe, and Rn. 

Differences in the size of the van der Waals forces can be used to explain the trend in the enthalpy change of vaporisation and boiling points of the noble gases. Figure 4.35 shows how these vary with the number of electrons present. (The enthalpy change of vaporisation is the energy required to convert a mole of liquid into a mole of gas.)... 

Figure 4.35 a Enthalpy changes of vaporisation and b boiling points of the noble gases plotted against the number of electrons present. 

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