A Basic Rule of Chemistry Can Be Broken, Calculations Show
A study suggests atoms can bond not only with electrons in their outer shells, but also via those in their supposedly sacrosanct inner shells
By Clara Moskowitz
Most of us learned in high school chemistry class that chemical bonds can only form when electrons are shared or given away from one atom’s outer shell to another’s. But this may not be strictly true. A chemist has calculated that under very high pressure not just the outer electrons but the inner ones, too, could form bonds.
Inside atoms, electrons are organized into energy levels, called shells, which can be thought of as buckets of increasing size that can each hold only a fixed number of electrons. Atoms prefer to have filled buckets, so if their outer shell is missing just one or two electrons, they are eager borrow form another atom that might have one or two to spare. But sometimes, a new study suggests, atoms can be incited to share not just their outer valence electrons, but those from their full inner shells. “It breaks our doctrine that the inner-shell electrons never react, never enter the chemistry domain,” says Mao-sheng Miao, a chemist at the University of California, Santa Barbara, and the Beijing Computational Science Research Center in China. Miao predicted such bonds using so-called first-principles calculations, which rely purely on the known laws of physics, and reported his findings in a paper published September 23 in Nature Chemistry. Such bonding has yet to be demonstrated in a lab. Nevertheless, “I’m very confident that this is real,” he says. (Scientific American is part of Nature Publishing Group.)
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Where the general rule that works under any condition you're likely to find can, under extreme conditions and (more likely "or"
in very rare instances, be broken.
Mostly because the "rule" isn't derived from primitives but is observationally based. Increase your observational base and, well, you have to change your rule. In this case, the real surprise is that this wasn't assumed to be the case straight along. Probably just one of those things nobody much thought about because it really doesn't much matter.
It's like "conservation of matter" that's the basis of a lot of chemistry. Yeah, it's wrong. So if you want your two points back, you got to give up a lot more.
Then there's "conservation of energy" that's the basis of a lot of engineering and physics. It's also wrong. No question.
Except that the "law of conservation of matter and energy," under which matter and energy are essentially treated as equivalent for some purposes, energy being transformed into matter (and vice-versa) isn't something that we control very well in most situations. We can get it to be triggered in nuclear reactors; in extreme situations in particle accelerations we can create matter; we rely on it when we have geothermal or solar power stations. But for 99.99999% of what we control, we really do assume that matter can't be created or destroyed and, likewise, energy can't be created or destroyed with very good results.