Home Insights into the crystal chemistry of Earth materials rendered by electron density distributions: Pauling’s rules revisited
Article
Licensed
Unlicensed Requires Authentication

Insights into the crystal chemistry of Earth materials rendered by electron density distributions: Pauling’s rules revisited

  • G.V. Gibbs EMAIL logo , Nancy L. Ross , David F. Cox and Kevin M. Rosso
Published/Copyright: May 15, 2014
Become an author with De Gruyter Brill

Abstract

Experimental and calculated electron density distributions determined for oxide and silicate crystals and siloxane molecules provide a new basis for addressing the classic foundation of the crystal chemistry of silicates, including atomic/ionic radii, the radius ratio rule and the nexus between the Pauling’s bond strength, resonance bond number, and bond length. The distributions indicate that the charge density of a bonded oxygen atom is highly distorted with its bonded radius decreasing systematically from 1.50 Å when bonded to highly electropositive atoms like sodium to ~0.65 Å when bonded to highly electronegative atoms like nitrogen. Rather than a single radius, the atom has as many bonded radii as it has bonded interactions. Bonded radii determined for the metal atoms match the Shannon effective ionic radii for the more electropositive atoms, but they depart and decrease systematically as the electronegativity of the M atoms increases. Pauling’s first rule is considered to be irrelevant given the asphericity and the range of the bonded radii displayed by the O atom.

A power law regression expression is formulated between the average M-O bond lengths, <R(M-O)>, and the average value of the electron density, <ρ(rc)> = r[1.41/<R(M-O)>]4.76, at the bond critical point, rc, between pairs of bonded M-O atoms. The expression applies to a host of crystals and molecules comprising M-atoms for all rows, r, of the periodic table. The <ρ(rc)> values correlate with bond strength and resonance bond strength for the M-O bonded interactions on a one-to-one basis, demonstrating that the Pauling bond strength is a direct measure of the electron density involved in a bonded interaction and the accumulation of the electron density between the bonded pair. The widespread applications of the Brown-Shannon bond valence model in the Earth sciences and material science owes much of its success to the direct connection that exists between bond strength and the quantum mechanical observable, the electron density distribution. Compelling evidence is presented that supports the argument that the Si-O bonded interactions within siloxane molecules and silicate crystals are fundamentally the same, and that the local Si-O bonded interactions comprising molecules are, at the very core, equivalent to the Si-O bonded interactions observed in silicate crystals. Bond paths between the O atoms comprising shared polyhedral edges are consistent with Pauling’s third rule, the shorter the O-O shared edges, the greater the accumulation of the electron density between the O atoms, the greater the stabilization of the shared edges.

Published Online: 2014-5-15
Published in Print: 2014-5-1

© 2014 by Walter de Gruyter Berlin/Boston

Articles in the same Issue

  1. Highlights and Breakthroughs
  2. Absence of pressure-induced electron spin-state transition of iron in silicate glasses upon compression
  3. Dolomite discloses a hidden history of subducting slabs
  4. Crossroads in Earth and Planetary Materials
  5. Crystal structures of laihunite and intermediate phases between laihunite-1M and fayalite: Z-contrast imaging and ab initio study
  6. Minerals in the Human Body
  7. A novel technique for fluorapatite synthesis and the thermodynamic mixing behavior of F-OH apatite crystalline solutions
  8. Volcanic Rocks
  9. The cooling kinetics of plagioclase feldspar as revealed by electron-microprobe mapping
  10. Spinels Renaissance–Past, Present, and Future
  11. High-pressure behavior of thiospinel CuCr2S4
  12. Martian Rocks and Soil
  13. Mössbauer parameters of iron in phosphate minerals: Implications for interpretation of martian data
  14. A temperature-controlled sample stage for in situ micro-X-ray diffraction: Application to Mars analog mirabilite-bearing perennial cold spring precipitate mineralogy
  15. Detection of iron substitution in natroalunite-natrojarosite solid solutions and potential implications for Mars
  16. Articles
  17. Harmunite CaFe2O4: A new mineral from the Jabel Harmun, West Bank, Palestinian Autonomy, Israel
  18. An assessment of the reliability of melt inclusions as recorders of the pre-eruptive volatile content of magmas
  19. Beryllium mineral evolution
  20. Incorporation of Y and REEs in aluminosilicate garnet: Energetics from atomistic simulation
  21. Role of silica for the progress of serpentinization reactions: Constraints from successive changes in mineralogical textures of serpentinites from Iwanaidake ultramafic body, Japan
  22. Ophirite, Ca2Mg4[Zn2Mn23+(H2O)2(Fe3+W9O34)2]·46H2O, a new mineral with a heteropolytungstate tri-lacunary Keggin anion
  23. Bubble formation during decompression of andesitic melts
  24. Manganese carbonate formation from amorphous and nanocrystalline precursors: Thermodynamics and geochemical relevance
  25. Insights into the crystal chemistry of Earth materials rendered by electron density distributions: Pauling’s rules revisited
  26. Adsorption of sulfur dioxide on volcanic ashes
  27. Sulfidation of native gold
  28. Electrical conductivity of synthetic mullite single crystals
  29. In situ Raman spectroscopy identification of the S3̅ ion in S-rich hydrothermal fluids from synthetic fluid inclusions
  30. Melting phase equilibria of model carbonated peridotite from 8 to 12 GPa in the system CaO-MgO-Al2O3-SiO2-CO2 and kimberlitic liquids in the Earth’s upper mantle
  31. Effect of orientation on ion track formation in apatite and zircon
  32. Major, minor, and trace element composition of pyromorphite-group minerals as recorder of supergene weathering processes from the Schwarzwald mining district, SW Germany
  33. Toward an accurate ab initio estimation of compressibility and thermal expansion of diamond in the [0, 3000 K] temperature and [0, 30 GPa] pressures ranges, at the hybrid HF/DFT theoretical level
  34. Vanadio-oxy-chromium-dravite, NaV3(Cr4Mg2)(Si6O18)(BO3)3(OH)3O, a new mineral species of the tourmaline supergroup
  35. Graţianite, MnBi2S4, a new mineral from the Bǎiţa Bihor skarn, Romania
  36. Letters
  37. Microporous gold: Comparison of textures from Nature and experiments
  38. Valence state partitioning of V between pyroxene and melt for martian melt compositions Y 980459 and QUE 94201: The effect of pyroxene composition and crystal structure
  39. MSA Award Presentations
  40. Presentation of the Mineralogical Society of America Award for 2013 to Wendy Li-Wen Mao
  41. Acceptance of the Mineralogical Society of America Award for 2013
  42. Presentation of the 2013 Roebling Medal of the Mineralogical Society of America to Frank C. Hawthorne
  43. Acceptance of the 2013 Roebling Medal of the Mineralogical Society of America
  44. Presentation of the Distinguished Public Service Award for 2013 of the Mineralogical Society of America to Pierrette Tremblay
  45. Acceptance of the Distinguished Public Service Award for 2013 of the Mineralogical Society of America
  46. Presentation of the Dana Medal of the Mineralogical Society of America for 2014 to Patricia Dove
  47. Acceptance of the Dana Medal of the Mineralogical Society of America for 2014
  48. Book Review
Downloaded on 8.9.2025 from https://www.degruyterbrill.com/document/doi/10.2138/am.2014.4660/html
Scroll to top button