Making New Elements Gets a Lot Harder From Here
Discovering an element isn’t like it was in the good old days. Back then, you could isolate oxygen simply by burning a little mercuric oxide. Now scientists spend years using massive particle accelerators to smash barely-there specks of matter together. And in the one in a trillion chance the right pair of atoms happen to smash together and become one, what do the scientists have? Not a lump of unobtanium, but a bunch of computer gibberish saying the new atom managed to stay stable for a fraction of a second before decomposing into nothingness. Congratulations on your new element, kiddos.
So long to the days of the lone genius, too. It took more than 100 scientists—distributed across four teams in three countries—to discover four new elements, just added to the periodic table last week. Yet to be named, these four elements are so-called super-heavies, with nuclei so dense that they can’t exist in nature. This discovery completes the periodic table’s seventh row, or period, and puts researchers closer to reaching chemistry’s most fabled destination: the island of stability, a point at which a super-heavy element can exist on its own. But getting there means more particle colliders and more years of research—all with the added challenges of relativistic mechanics.
Super-heavy elements are those with an atomic number of 100 or higher, meaning their nuclei contain 100 or more protons. Protons are positively charged, which means they repel each other if they get too densely packed. In lighter elements, the weak nuclear force exerted by neutrons and other particles counteracts the protons’ repulsive force enough to stabilize the nuclei. “Once you get bigger nuclei, there are so many particles that it can’t keep itself together for very long,” says Dawn Shaughnessy, project leader of the Lawrence Livermore National Laboratory heavy element program that co-discovered the four new elements, along with two other super-heavies.
Even in the vast probabilities of the universe, where things like diamond-cored planets and time-devouring black holes exist, super-heavies are super rare. “If we assume that physics is physics wherever we go, there could be a supernova where super-heavy elements exist for a millisecond or so,” says Shaughnessy. But the best bet for finding these elements on Earth is a particle accelerator, where scientists try to build super-heavies by adding together the nuclei of smaller elemental atoms.
For example, to create element 117, Shaughnessy’s colleagues smashed calcium (atomic number 20) into berkelenium (atomic number 97). “If you add that up you get 117,” she says. “We really are just fusing the protons together to make the new element.”
Which takes some finesse. The atoms meant for intercept need enough energy to overcome the repulsive force of all the protons getting mushed together, otherwise their nuclei will ricochet off each other. On the other hand, if the atoms have too much energy, the nuclei just obliterate one another on impact. “There’s a sweet spot to get them to come together and merge,” says Paul Karol, chair of the International Union of Pure and Applied Chemistry’s joint working party for discovering new elements. Figuring that energetic sweet spot takes a lot of experimentation, guesswork, and luck.
Once they’ve calibrated the energy, they just fire atoms until some happen to collide. This can take months, years even. But once it happens, and the computer records it, scientists can record the element’s properties, and work toward finding heavier elements.
So what’s the point? Theoretically, scientists will eventually find a super-heavy that is stable enough to exist for longer than a millisecond. This stability comes from having the right number of weak force-emitting neutrons to balance out the protons’ repulsivity. That perfect balance is found in a theoretical region called the island of stability, a point beyond the normal range of stable nucleic organizations. A super-heavy in the island of stability could have outstanding properties.
Does that mean science is on its way to finding materials like dilithium (atomic number 119), which helped Star Trek‘s space craft travel faster than light? No chemist serious about her geek cred is going to say no outright. But if stable super-heavies do exist, they probably will only last on the order of hours or days. And you’d need one hell of a particle collider to accumulate enough smushed-together atoms for a crystal large enough to power a warp drive. Which kind of puts a logistical cramp on the whole space travel thing. Theoretically speaking, that is. “I’m more of a Star Wars person anyway, so I can’t really comment on dilithium,” says Shaughnessy.
And because these four newest elements closed out the periodic table’s seventh row (or period), discovering the next row is going to be extra tough. As elemental nuclei get more massive, the electrons orbiting them get more energetic. In eighth period elements, those electrons are so energized that they are traveling at nearly light speed. If you remember your Einstein, when an object’s velocity approaches light speed, its mass and energy are correspondingly affected. Now you’re dealing with all sorts of weird quantum effects that scramble everything that normally makes sense to chemists. “That turns something which was merely complicated into something incredibly complicated,” says Karol.
Even the periodic table’s core logic could start to break down. “Element 114 is a great example,” says Shaughnessy, of one of her previous discoveries. It sort of looked like a metal, and sort of looked like a gas—except it’s nowhere near the rest of the noble gases on the periodic table. It’s things like this that make chemists question whether their entire discipline has any order. Damn you upstart kids, is nothing sacred?
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