At 1 atm the P V term is negligible, and the crystal structure assumed is the one that minimizes the internal energy. With increasing pressure the P V term begins to dominate, first favoring structures with smaller volumes where van der Waals space has been squeezed out. By 100 GPa the magnitude of the P V term becomes comparable to the energy of a chemical bond (∼1 eV), so the most stable structures possess bonding motifs that differ drastically from those preferred at 1 atm. And, at 10-100 TPa, the energy associated with the P V term becomes comparable to the energies of the core orbitals (keV), while at the quantum unit of pressure (E Hartree /a 3 Bohr = 29.4 TPa) the shell structure of atoms is disrupted. 17 Therefore, the chemical trends taught and learned in School, and the properties of the elements used to infer the Periodic Table, change under pressure (Figure ). What might the Periodic Table look like if humans experienced 100 GPa or 1000 GPa in their daily lives?