> The bit about compressibility tickles my mind. One of my favourites is 'electride' bonding, where you compress a crystal so much that the electrons get squee

> The bit about compressibility tickles my mind. One of my favourites is 'electride' bonding, where you compress a crystal so much that the electrons get squeezed into the gaps (interstices) between atoms instead, essentially making the electrons themselves act as anions. This is really cool, and makes you wonder what other exotic high-pressure physics waits to be found. https://www.nature.com/articles/nchem.2254 https://www.nature.com/articles/nchem.2254