Understanding chemistry using fully relativistic quantum calculations

baker test

Making a chemical with electrons that move at 80% the speed of light
[Via Ars Technica]

Sometimes, getting exactly the result you predict is more exciting than it sounds. Last week, Science published a paper about creating chemical compounds with element 106, Seaborgium. A quick glance at the abstract showed that this chemical behaved similarly to the one made of Sg’s lighter cousin, tungsten. That sounds a bit dull—in fact I skipped covering it last week for precisely this reason—until you find out that you wouldn’t necessarily expect this result.

Admittedly, just getting the experiment done at all is pretty impressive. The isotope of seaborgium used, 265Sg, has a half-life of only 16 seconds. It has to be produced in a particle accelerator, which means it’s normally rather energetic and part of a cloud of energetic debris. So, the technique involved slowing it down and separating it, letting it undergo a chemical reaction, and only then could they characterize something about the resulting chemical’s behavior.

In this case, the researchers reacted it with carbon monoxide to form Sg(CO)6. The resulting chemical stuck to a silicon dioxide surface briefly before the Sg decayed, allowing a very basic characterization of its chemical behavior. And, as noted above, it behaved similarly to the tungsten version of the same compound.


Yep, the only way to understand the chemistry of some of these unusual elements is to include ‘unreal’ quantum effects on particles moving at almost light speed.

Here, the proper chemistry could only be determined by realizing that the electrons of Seaborgium are moving (if we can use that word) at 80% light speed. In hydrogen, the electrons travel at about 1% the speed of light.

Relativistic quantum mechanics are responsible for many weird things in the physics world. They are invading the chemical world. 

What is cool – Seaborgium (element #106) is named after Glenn Seaborg who proposed an island of stability up around element #115. Understanding the chemistry of seaborgium may help us get there.

Seaborg is one of the greats of the 20th century, not only discovering plutonium and figuring out how to isolate it, his work redrew the Periodic table. He patented americium which helped him in his old age. He worked hard for arms control, ran the Atomic Energy Commission and, as chancellor of UC Berkeley  he relaxed control of political speech in the lat 50s.

The pictire above is from the Baker test at Bikini atoll, the first underwater explosion that resulted in so much radioactive contamination that further tests were canceled. Glenn Seaborg called it the first atomic disaster.