Estimation of thermodynamic and physicochemical properties of the alkali astatides: On the bond strength of molecular astatine (At<sub>2</sub>) and the hydration enthalpy of astatide (At<sup>−</sup>)
Bibliographic record
Abstract
Abstract The recent accurate and precise determination of the electron affinity ( EA ) of the astatine atom At 0 warrants a re‐investigation of the estimated thermodynamic properties of At 0 and astatine containing molecules as this EA was found to be much lower (by 0.4 eV) than previous estimated values. In this contribution we estimate, from available data sources, the following thermodynamic and physicochemical properties of the alkali astatides (MAt, M = Li, Na, K, Rb, Cs): their solid and gaseous heats of formation, lattice and gas‐phase binding enthalpies, sublimation energies and melting temperatures. Gas‐phase charge‐transfer dissociation energies for the alkali astatides (the energy requirement for M + At − ➔ M 0 + At 0 ) have been obtained and are compared with those for the other alkali halides. Use of Born‐Haber cycles together with the new AE (At 0 ) value allows the re‐evaluation of Δ H f (At 0 ) g (=56 ± 5 kJ/mol); it is concluded that (At 2 ) g is a weakly bonded species (bond strength <50 kJ/mol), significantly weaker bonded than previously estimated (116 kJ/mol) and much weaker bonded than I 2 (148 kJ/mol), but in agreement with the finding from theory that spin‐orbit coupling considerably reduces the bond strength in At 2 . The hydration enthalpy (Δ H aq ) of At − is estimated to be −230 ± 2 kJ/mol (using Δ H aq [H + ] = −1150.1 kJ/mol), in good agreement with molecular dynamics calculations. Arguments are presented that the largest alkali halide, CsAt, like the smallest, LiF, will be only sparingly soluble in water, following the generalization from hard/soft acid/base principles that “small likes small” and “large likes large.”
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".