India, Sept. 4 -- Nitrogen is remarkable.

That breath you just took is four-fifths nitrogen, but the gas does pretty much nothing to you or for you. Nitrogen in the air is essentially unavailable to living things, and yet, in one of those delicious paradoxes, all life depends on nitrogen's unique ability to hold its electrons close, but not too close.

Electrons are a key currency of the chemistry of life, and that makes nitrogen a key player in how the molecules of life get built. Every amino acid and every rung of our DNA depends on it.

Mediating this paradox - abundant but unavailable, scarce but necessary - is a bond. In the atmosphere, two nitrogen atoms clasp each other with a triple bond that is one of the strongest in all of che...