Paradigms and paradoxes:: Accidental degeneracies, I:: Suppose the 2s and 2p orbitals were closer in energy.: How would organic chemistry be different?

Hypothesized accidental orbital degeneracies, from origins other than symmetry, in the second principal quantum level lead to surprising new chemistry of carbenes, aromatic compounds, and, most interestingly, to a possible new allotrope of carbon. Consequences of degeneracies in the transition metals are hinted at.