Extreme chemistry explores how matter behaves under immense pressures (up to millions of atmospheres, or terapascals) and temperatures, representing a fundamental departure from the chemistry known at Earth's surface. Under extreme conditions, the pressure-volume ($PV$) term in the Gibbs free energy equation dominates over standard electrostatic interactions, physically forcing atomic and molecular structures to reconfigure to achieve lower enthalpy. As atoms are crushed together, the Pauli exclusion principle dictates that their electron clouds overlap, which leads to electron delocalization, new orbital hybridizations, and entirely novel chemical bonding motifs.

This extreme environment blurs the traditional rules of the periodic table. Typically inert noble gases, such as helium and xenon, can react to form stable compounds like $Na_2He$ ...