As a 17-year-old first year college student a half century ago, I learned that pure carbon was the only ingredient in pencil “lead” (graphite), as well as diamond.  That little bit of knowledge seems to have guided my professional life ever since, as my fascination with this has not waned over all these years.  In the graphite-diamond example, chemists understand/explain this carbon atomic structure-property relationship using sp2/sp3 bond hybridization models, and physicists describe exactly the same thing in terms of valance and conduction band electronic structure. The latter model, developed from the standpoint of quantum mechanics, is really handy when understanding graphene (a single sheet of carbon), and other nanomaterials which I find particularly fascinating. My long-range plan was to map this atomic structure-property relationship thinking into a better understanding of environmental Earth, and to find understanding on the mechanistic and practical sides of this endeavor.  But how?  To the best of my ability, I will give examples in this lecture, likely using the following disparate examples from our research over the years:  1) our discovery of the atomic structure of magnesium hydroxide sulfate hydrates, helping to explain its impact on hydrothermal venting systems and life in the oceans;  2) very early experiments with calcite and sorbed cations, like aqueous cadmium, proving that sorbed species can readily move into the host calcite phase through solid state diffusion;  3) our work on pyrite surface electronic structure and reactive sites, atomically resolved, and relating that to acid mine drainage; 4) experiments concerning hematite reactivity as a function of its size in the nanoscale regime, and its effects on manganese redox chemistry and groundwater chemistry in general; 5) determining the nature of the formation and atomic structure of green rust and its reactivity for metal transport; 6) discovery of massive titanium suboxide generation, its remarkable defect atomic structure, and its human lung toxicity; and 7) expanding these themes to global impact scenarios.

My scientific lifetime of using atomic structure-property relationships to understand environmental Earth

ACS Fall 2021

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