Mulliken electronegativity is a slightly different way of measuring electronegativity than is used in the Pauling table above. To find Mulliken electronegativity for a certain atom, find that atom's first ionization energy. This is the energy requires to make the atom discharge a single electron.


This is something you'll probably have to look up in chemistry reference materials. This site has a good table you may want to use (scroll down to find it).As an example, let's say that we're trying to find the electronegativity of lithium (Li). In the table on the site above, we can see that its first ionization energy is 520 kJ/mol.
 This is a measure of the energy gained when an electron is added to an atom to form a negative ion. Again, this is something you'll need to look up in reference material. This site has resources you may want to browse.The electron affinity of lithium is 60 KJ mol-1.
 When you're using kJ/mol as units for your energies, the equation for Mulliken electronegativity is ENMulliken = (1.97×10−3)(Ei+Eea) + 0.19. Plug your values into the equation and solve for ENMulliken.


In our example, we would solve like this:



ENMulliken = (1.97×10−3)(Ei+Eea) + 0.19
ENMulliken = (1.97×10−3)(520 + 60) + 0.19
ENMulliken = 1.143 + 0.19 = 1.333
Find the first ionization energy of your atom.
Find the electron affinity of the atom.
Solve the Mulliken electronegativity equation.
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