The performance of the shelf model is shown in the following diagrams. Measured values and two model calculations are compared.

The two diagrams show how entropy and thermocapacity develop as a function of temperature.

                           Measured Values                               Model Calculation (see 9.2 Nr. 7)

Model calcuation by the Thermulation-I program

As shown in Section 3.1, molar thermal capacities are entropy changes, more precisely: derivatives of entropy according to the logarithm of temperature. Since we do not assign a unit symbol to the logarithm of the temperature, the unit remains in the derivative. Therefore, it should not be surprising that we find in the usual tables also for entropy and thermocapacity the same units: J^.K^.mol^-1. From the point of view of energy quantization, it seems more sensible to specify the quotients S/R and C_p/R, since the number character of these quantities becomes clearer. The diagram that the model calculates with the Thermulation-I program shows that this program correctly calculates the basic course of entropy and thermal capacity. The model temperature 3.0 tu corresponds quite well to the standard temperature of about 300 K. The values on the vertical axis are calculated for 100000 particles and they are also model values which, of course, can not agree with the measured values. For the quality of the model, however, the relative course of the two curves correlates very well with the measured value profile.

The following periodic system shows that, under standard conditions within the main groups, the molar thermal capacities change substantially less than the entropy values. In the case of the noble gases, only the entropy values change, while the molar thermal capacities are constant.

The table above shows "atomic" entropy values. A detailed explanation of what is meant by this can be found in section 5.1. At this point, it is important to note that there are no differences between the elements with a few exceptions between molar and atomic values. The exceptions are the molecular gases.
In Section 3.5 you will find a detailed discussion about the different influence of the particle mass on entropy and thermal capacity.
Within a main group, the molar thermal capacities are slightly greater than the entropies from top to bottom (with decreasing forces). Since the additional mass inflow, which is also larger from the top downwards, is now missing, the change in the molar thermal capacity is less than in entropy. The diagram shows the results of the model calculation according to the shelf model with the Thermulation-I program. Compare this graph to the measurement data shown in section 3.4.

Model units