Is Pauling electronegativity well-defined?

Pauling's definition of electronegativity defines the difference of electronegativity between two elements.

Suppose three elements A, B, and C. Then we can calculate $ϰ_a - ϰ_b$, $ϰ_b - ϰ_c$, and $ϰ_c - ϰ_a$ independently. Is the sum of the three values always zero? Why?

• can you explain the symbols? What is "$ϰ$" in $ϰ_a - ϰ_b$? Feb 4, 2015 at 14:03

If you have a single, unique value of $\chi_i$ for each element $i$ then yes, the sum of the three values is always zero.
$${\chi}_{a}-{\chi}_{b}=(1\ eV)^{-\frac{1}{2}}\,\sqrt{{E}_{d}\left( a,b\right) -\frac{{E}_{d}\left( a,a\right) +{E}_{d}\left( b,b\right) }{2}}$$
where $E_d(i,j)$ is the dissociation energy for a single bond between element $i$ and element $j$. The definition assumes that you can consistently and accurately say that the square of the electronegativity difference between A and B is equal to the difference between the dissociation energy for AB and the average of the dissociation energies for AA and BB. If this isn't consistently true for each combination of three elements A, B, and C, your sum will be nonzero. Pauling fit his electronegativity values to the data to average out these inconsistencies.