Figure 1 and Figure 2 present the diagram of properties (Scores plot) and diagram of elements (loading plot), respectively that based on experimental data .
It allows us to detect the correlations between the 22 physical properties of the elements, which we noted Var1 to Var22 for better visibility of the diagram. The list of variables is as follows:
We can notice some correlations and anti-correlations. Some of these correlations are simple to explain. Others reflect intrinsic physical principles and relationships. In the list of correlations, we find:
-Var1 correlated to Var2: The atomic number and the atomic mass are correlated.
It's completely normal, as long as the atomic mass includes the sum of the masses of neutrons and protons. The number of these latter is precisely the atomic number Z.
-Var 1 and Var2 correlated to Var 16:
The heat capacity, atomic number, and atomic mass are correlated, which can explain as follows: The heat capacity expresses the ability of the material to assimilate heat.
The principal mode of heat energy assimilation is the phonons or vibrations of the network. The heavy atoms need more energy for exciting the phonons. In other words, they need more heat absorbed for giving a temperature increase.
-Var21 and Var 19 are correlated:
The melting temperature and the boiling temperature have a physical relationship. It is axiomatical, as long as the boiling occurs after fusion.
-Var19 and Var 21 have a relationship with Var20:
The melting and boiling temperatures correlate to the change in enthalpy at melting.
This last quantity expresses the energy which supplies so that the material passes from the solid to the liquid state.
Var13 and Var14 correlated to Var 9:
The elastic constants C11 and C12 and Young's modulus have relationships.
The two constants define the material response to deformation on the atomic scale. Young's modulus is the macroscopic response of the material to tensile deformation. Unquestionably, the macroscopic mechanical behaviour properties are expressions of the displacement of atoms on a smaller scale when applying an external constraint.
-Var4 correlated to Var5: electronegativity and the energy of the 1st ionization are correlated. An electronegative material tends to attract electrons from other atoms in a bond. A fortiori, the electrons of its last layer are strongly linked and are only very difficult to yield that expressed by high ionization energy.
-Var6 correlated to Var8: The network parameter and the molar volume are correlated, which is logic since the interatomic spacing is function volume.
-Var17, Var6, and Var8 are correlated:
The entropy has a relationship with the network parameter. Therefore, with the molar volume. It's' implies that the increase in molar volume increases the disorder in the system.
-Var10 correlated to Var11 and Var12: the elasticity constants S11, S12, and S44 are all correlated. This fact is consistent as long as all these quantities are directly related to how the structure varies when the external stress is applied. In other words, they all arise from the interatomic bond.
On the other hand, we find the anti-correlations
-Var14 has an inverse correlation to Var6 and Var8:
Young's module has an inverse correlation to the network parameter and the molar volume.
It's known from experience that Young's module is proportional to the compression module that measures the network compressibility. So as important as it is, it is difficult to compress the network.
When the lattice parameter and the molar volume decrease, the volume per atom also decreases. By consequence, the atom's possibility to bring closer together decreases.
It explains why the network parameter decreases the compression module as much, and therefore Young's module increases.
-Var1 and Var2 have an inverse correlation with Var4 and Var5: the atomic number and mass are inversely proportional to the electronegativity and the energy of first ionization.
When the number of electrons in the atom increases, the distance between the valence electrons and the nucleus increases.
Consequently, the decreases of electrons implied less energy required to tear them away (first ionization energy) decreases.
Also, when the number of electrons increases, the electronegative decreases, and its' nucleus doesn't attract electrons from neighbouring atoms more strongly.