Revising Activity Series for Elements: A Personal Endeavor

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SUMMARY

This discussion focuses on the revision of the activity series for elements, specifically through the lens of electronegativity and ionization energies. The participant seeks to understand how Linus Pauling developed his electronegativity scale and is interested in other scales such as the Mulliken and Allred-Rochow scales. The conversation highlights the need for a real unit to compare electronegativity with ionization energy, emphasizing that electronegativity is a unitless ratio derived from bond energies. The participant expresses satisfaction with the clarification that electronegativity, while unitless, has a solid mathematical foundation.

PREREQUISITES
  • Understanding of electronegativity scales (Pauling, Mulliken, Allred-Rochow)
  • Basic knowledge of ionization energy and its units (kJ/mol)
  • Familiarity with half-cell reactions and electrochemical potentials
  • Concept of unitless quantities in scientific measurements
NEXT STEPS
  • Research the mathematical derivation of Pauling's electronegativity scale
  • Explore the Mulliken scale and its application in chemistry
  • Investigate the Allred-Rochow scale and its significance in electronegativity
  • Learn about the relationship between bond energies and electronegativity
USEFUL FOR

High school chemistry students, educators in chemistry, and anyone interested in the mathematical foundations of electronegativity and its application in chemical bonding.

pearbear21
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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.
 
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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.ausetute.com.au/bondpola.html
http://www.ucdsb.on.ca/tiss/stretton/Database/electronegativity.htm

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

The Bob (2004 ©)
 
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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.
 
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.
 
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.
 
Gokul43201 said:
Since it is a ratio of energies, it is unitless.
The exact reason I stated it as a shocked question. Atleast I know for sure, suer, sure now.

The Bob (2004 ©)
 

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