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Name: Bob
Status: student
Age: 17
Location: N/A
Country: N/A
Date: 2/26/2004


Question:
I am confused between electronegativity and electron affinity. Do these two properties correlate since both involve attraction of electrons by a nucleus?


Replies:
Hi Bob,

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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