In diatomic molecules (e.g., ${\mathrm{P}}_{2}$) the distinction is made between the quantization of the electrons of the atomic cores (${\mathrm{P}}^{5+}$), which is assumed to be the same (${1}^{2}$${2}^{8}$) as in the free atom (P), and of the valence electrons ${3}^{2,2}$(${\mathrm{P}}^{5+}$)${\mathrm{II}}^{2}$(${\mathrm{P}}^{5+}$)${3}^{2,2}$. The latter can be quantized with respect to the field of both cores ("shared" ${\mathrm{II}}^{2}$ electrons) and to the field of single cores ("unshared" ${3}^{2,2}$ electrons). The Pauli principle is applied separately to the quantization of the "shared" electrons and to the others. On this basis it is possible to interrelate the great difference in the strength of the external field (intermolecular forces) of ${\mathrm{N}}_{2}$ and ${\mathrm{P}}_{2}$ with the size of the atomic cores ${\mathrm{N}}^{5+}$ and ${\mathrm{P}}^{5+}$. The comparison of the intramolecular binding strength in ($\mathrm{AB}$) with that in ${(\mathrm{AB})}^{+}$ supports the conclusions: in ${\mathrm{N}}_{2}$ all ten (not merely six) valence electrons, in HCl all eight (not two) participate in the binding of the cores ${\mathrm{N}}^{5+}$ and ${\mathrm{N}}^{5+}$, ${\mathrm{H}}^{+}$ and ${\mathrm{Cl}}^{7+}$; the molecules of monohydrides of positively di- and trivalent elements, like those of positively monovalent elements, contain hydrogen as a more of less strongly deformed ${\mathrm{H}}^{\ensuremath{-}}$.