Johannes Stark

If the experimental physicist has already done a great deal of work in this field, nevertheless the theoretical physicist has still hardly begun to evaluate the experimental material which may lead him to conclusions about the structure of the atom.

Boron is carbon's neighbor on the periodic table, which means it can do a passable carbon impression and wriggle its way into the matrix of a diamond. But it has one fewer electron, so it can't quite form the same four perfect bonds.