Tag: Main Group Chemistry

Inorganic Chemistry · Main Group Noble Gas Compounds: Why Xenon Reacts and Helium Does Not The elements once believed inert form a well-defined set of compounds, and which ones form is entirely predictable from ionisation energy. BSc & MSc · Inorganic Chemistry · Concept The short answer: Xenon has a low enough ionisation energy to be oxidised by fluorine and oxygen. Its fluorides have structures predicted correctly by VSEPR once the lone pairs are counted, and the fluorides hydrolyse to oxides and oxofluorides. Helium and neon do not react, because their ionisation energies are far too high. Why xenon and…

Read More

Inorganic Chemistry · Main Group Boranes and Wade’s Rules: Predicting Cluster Shapes Boron clusters look chaotic until you count skeletal electron pairs. Then each structure follows from a single number. BSc & MSc · Inorganic Chemistry · Method The short answer: Count the skeletal electron pairs. For n boron vertices, n+1 pairs gives a closo structure, n+2 gives nido, n+3 gives arachno. Each type is derived from the closo polyhedron by removing vertices, so the shapes are related rather than independent. Why boranes need special treatment Boron has three valence electrons but four valence orbitals, so it cannot form enough…

Read More