Sometimes, chemistry torpedoes your view of the world. Take hydrogen, for example. Scientists are extraordinarily close to turning the universe’s most abundant element—which is almost always found as either a gas or a plasma—into a metal.
Researchers have been probing hydrogen’s different phases for decades, and metallic hydrogen was first proposed over 80 years ago by two Princeton physicists. Now, three physicists based in Scotland have created a fifth phase of hydrogen, one that’s definitely not a gas and quite probably almost a metal.
To get there, the team squished hydrogen molecules (H 2 ) between diamond anvils at some of the highest pressures ever produced in a lab—380 gigapascals, or about 3.75 million times more pressure than is found at sea level. At that point, the hydrogen ceased to be transparent and turned very dark, a sign that the usual covalent bond was breaking down. It all took place at a relatively balmy 300 K, or about 80˚ F.
Here’s John Timmer, writing for Ars Technica:
Since some signs of a bond are still present, the authors posit that this represents a new phase of hydrogen accompanying the gas and more readily achieved liquid forms. Because of some other exotic phases discovered in the search for hydrogen metal, this one is named phase V. The authors don’t think that it represents a fully metallic form, since there are some signs that the bonds between hydrogen atoms are still present. But they’re clearly not as robust as they were, so the authors speculate that it represents “the onset of the predicted non-molecular and metallic state of hydrogen.”
The researchers suspect that just a little more pressure will finally eliminate the bonds and create truly atomic, metallic hydrogen.
Photo credit: Philip Dalladay-Simpson and Eugene Gregoryanz