Electronegativity and Electron Affinity
I am confused between electronegativity and electron affinity. Do these two
properties correlate since both involve attraction of electrons by a nucleus?
They do correlate with each other as broad trends in
the periodic table. Nice observation!
In fact, R. Mulliken proposed an electronegativity scale as follows:
X =( K * (|EA| + |IE|) / 2) - A
where X = Mullekin electronegativity
K and A are constants chosen to bring the scale to values which
are similar to Pauling's scale (which ranges from 0 to 4 or so
and was designed using bond energies)
|EA| = magnitude of electron affinity
|IE| = magnitude of ionization energy
X is supposed to describe the net attraction of an element's
atoms to valence electrons. |EA| is the amount of energy released
when an extra electron is attached to a neutral gas-phase atom.
|IE| is the amount of energy required to remove a single electron
from a neutral gas-phase atom. The harder it is to remove an
atom's valence electrons, AND the easier it is to attach extra electrons,
the greater the electronegativity. This is why all three quantities have
the same broad trends across the periodic table (although the devil
is in the details sometimes, so to speak).
Best, Dr. Topper
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Update: June 2012