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Primary-Source Investigation

Argon–Krypton Electron Gain Enthalpy Investigation

Late July 2026Phase IV — Historical Investigation

Primary-Source Investigation

With the methodology established, the next step was to examine the primary literature itself.

Rather than relying on textbook summaries or secondary reviews, I read the foundational papers that shaped the modern understanding of electron affinities.

Each paper was evaluated using the same checklist:

  • Does argon appear?
  • Does krypton appear?
  • Is an electron affinity reported?
  • Is the value experimental or theoretical?
  • What earlier work is cited?
  • Does the paper justify the reported conclusions?

The objective was simple.

Separate what the original literature actually says from what later educational sources repeat.

Objective

Determine whether the foundational electron-affinity literature assigns positive electron affinities to argon or krypton.

Motivation

If the commonly reported values originate in the scientific literature, they should appear explicitly in the foundational references.

If they do not, the historical trail itself becomes an important research question.

Work Performed

The following primary references were examined:

  • Pritchard (1953)
  • Berry (1969)
  • Hotop & Lineberger (1975)
  • Hotop & Lineberger (1985)

For each paper, the discussion of argon and krypton was recorded independently before drawing any overall conclusions.

Results

Pritchard (1953)

🟢 Verified

  • No electron affinity is assigned to argon.
  • Krypton is not discussed.

Berry (1969)

🟢 Verified

  • No electron affinity is assigned to argon.
  • Krypton is not discussed.

Hotop & Lineberger (1975)

🟢 Verified

  • Argon is reported as having
EA<0.EA < 0.
  • Krypton is also reported as having
EA<0.EA < 0.

Hotop & Lineberger (1985)

🟢 Verified

  • Argon is reported as
EA<0.EA < 0.
  • Krypton is likewise reported as
EA<0.EA < 0.
  • The paper discusses a metastable excited state of Ar⁻ but does not assign a stable ground-state electron affinity.

Overall Conclusion

Across the four foundational references examined,

🟢 Verified

No paper assigns a positive electron affinity to either argon or krypton.

Instead, the later review articles explicitly recommend

EA<0EA < 0

for both atoms.

This result represented the first major historical finding of the investigation.

Research Notes

At this stage, the investigation had answered an important question.

It was no longer necessary to ask whether the primary literature supported the commonly quoted textbook values.

It did not.

A different question had now emerged.

If these papers never reported the familiar positive values, where did those values originate?

Next Steps

Trace the historical origin of the commonly quoted value of approximately +96 kJ/mol through textbooks, reference works, and citation chains until its earliest documented source can be identified.