Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Pauling scale

  1. Aug 28, 2005 #1
    All right, before reading this, please understand that I am only in my second year of study in high school. Bear with me...

    When looking at the activity series or metals and comparing it to the electronegativity and ionization energies of the elements, I noticed something quite interesting that I would like to tweak on my own accord. I won't go into the details here, but it deals with creating a revised table of activities for the elements based on a more solid approach. None of this is for school, simply personal endeavor.

    Now, what I need to know is HOW Pauling developed his scale mathematically and in case it is as arbitrary as it seems, I would like to know of any other valid measurements of electronegativity that have come to be. Why I ask for these, is to find a scale that has some sort of REAL unit. I need a real unit that I could compare to the kJ/mol measurement of ionization energy, allowing subtraction possibly. I can't work with them the way they are, obviously. It's like adding apples and oranges.
  2. jcsd
  3. Aug 28, 2005 #2
    Are you asking for a measurement of electronegativity in kJ mol-1?

    Well anyway, I think there are only three measuring scales: The Mulliken scale, The Pauling scale and The Allred-Rochow scale.

    Try looking:
    http://www.ucdsb.on.ca/tiss/stretton/Database/electronegativity.htm [Broken]

    I can't say I fully understand why or what you are looking for but I will try to help.

    The Bob (2004 ©)
    Last edited by a moderator: May 2, 2017
  4. Aug 29, 2005 #3
    Electronegativity in kJ mol^-1 would be amazing. I just need some sort of real value like that. Thanks much for naming a few other scales for me. That should prove to help me. I haven't been able to find out if they use any type of unit I could use, but with more research, I'm sure I will figure it out. If anyone KNOWS mathematical values for electronegativity, please speak up. Thanks.
  5. Aug 30, 2005 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Ionization energies are quantities of energy and hence have units of energy (kJ/mol). Electronegativities are not, and so can not be expected to have such units. As for the activity series, the half-cell reactions have associated value of potentials (in volts), from which energies can be derived (G = -nFE). So, the activity series is based on solid mathematical values.

    Just because the Pauling (or Sanderson, or Allred or Mulliken-Jaffe or Allen) Electronagativity is a unitless number does not mean it has no strict mathematical basis. Consider other such unitless quantities like the dielectric constant, or relative premeability, or emissivity. They are all corrections to some "ideal" quantity and are hence unitless. The same is true with electronegativity. Pauling's electronegativity is a correction factor that relates the excess bond energy of an ionic bond (A-B) over the mean value of the parent covalent bonds (A-A, B-B). Since it is a ratio of energies, it is unitless.
  6. Aug 30, 2005 #5
    PERFECT. Thank you much for the very informative response. This is exactly the type of answer I was looking for, and it all makes sense now. I was just getting frustrated... not a single teacher or professor I have spoken to was able to explain it or even understood it themselves.
  7. Aug 31, 2005 #6
    The exact reason I stated it as a shocked question. Atleast I know for sure, suer, sure now.

    The Bob (2004 ©)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook