The method of linear combinations of connectivity indices has been app
lied to fit the following physicochemical properties of inorganic mole
cules: the lattice enthalpies of 32 inorganic compounds, the limiting
enthalpies of solution of 12 metal halides, the unfrozen water content
, the relative humidity and eutectic temperature of metal chlorides an
d the unfrozen water content of a mixed set of amino acids and metal c
hlorides. The achieved fit is very satisfactory and it can be normally
attained with the help of a single-index linear combination. The obta
ined fit draws also a validity test for the delta delta(upsilon) valen
ce number of the inorganic compounds and for a newly defined D-Z index
based on the number of valence electrons and on the principal quantum
number. The fit of the unfrozen water content of the mixed set of ami
no acids and metal chlorides, achieved by means of linear combinations
of reciprocal connectivity indices can be seen as a first hint far th
e construction of a connectivity model encompassing both organic and i
norganic compounds.