Hydrogen a Non Metal

[jeffy]

Roger's post was wrong. You need to cool hydrogen to make it metallic. Paul Robbins was right.

Originally Posted by Paul Robbins

Under high pressure/at low temperatures, hydrogen liquefies. It is then known as metallic hydrogen.

Earth's magnetic field is generated by its liquid metallic core swirling around as the planet spins.

Jupiter's much larger magnetic field needs a liquid metallic core swirling around to generate it. The metal in Jupiter's case is liquid hydrogen.

[KathChem82]

Please help me understand the question more. What kind of metallic hydrogen are we talking about here? Is it hydrogen with the properties of metals? Conductor of heat and electricity, solid, malleable, ductile, lustrous, etc? At the sub-atomic level, although a hydrogen atom is a nonmetal, it resembles the metals in its capacity to form a cation. Right?

[jeffy]

At high pressures hydrogen becomes metallic. The electrons are free to move around the hydrogen and it is a good conductor of heat and electricity.

http://csep10.phys.utk.edu/astr161/l.../interior.html

[cornball]

That seems crazy that hdyrogen can be a metal AND a non metal. We were taught it was a non metal.

[Paul Robbins]

Originally Posted by cornball

That seems crazy that hdyrogen can be a metal AND a non metal. We were taught it was a non metal.

All we're really saying is that, at enormous pressures, hydrogen has different properties than it does under the pressures we're more familiar with. At low pressures it's an insulator. At very high pressures, its electrons can move freely around and it becomes a conductor. (Remember, the terms metal and non-metal have been made up by humans for our convenience.)

Liquid, metallic hydrogen has been made at Lawrence Livermore National Laboratory.

At normal pressure, "condensed molecular hydrogen has a wide band-gap (about 15 electron volts), making it a transparent insulator, like glass."

"Our studies show that when shocked multiple times in a very cold liquid state, hydrogen becomes first a semiconductor and then a fluid metal when, as its density increases, its temperature becomes equal to the band-gap at about 0.3 electron volts (Figure 3).

At this point, all the electrons that can be excited by the shock to conduct electricity have been excited. Insensitive to further decreases in band-gap, the conductivity stops changing. Our conductivity data for hydrogen are essentially the same as those for the liquid metals cesium and rubidium at 2,000 K undergoing the same transition from a semiconducting to metallic fluid.

https://www.llnl.gov/str/Nellis.html

Here's their graph of hydrogen's resistance falling as pressure increases.

[KathChem82]

That seems crazy that hdyrogen can be a metal AND a non metal. We were taught it was a non metal.

Well the states of matter of the elements in the periodic table are under normal conditions. This can be thought of being at room temperature and a normal atmospheric pressure of around 1 atmospheres. The same is true with other substances such as water. We know water to be liquid under normal conditions. Changing the conditions however can also change the state of water. Lowering the temperature makes it a solid and increasing the temperature makes it a gas. It is also the same with the elements in the periodic table. Changing the conditions can change their states of matter.

[cornball]

nice. Hydrogen becomes a metal at 1.4 megabars!! Would you get that pressure at the bottoms of the oceans?

[firebird]

Originally Posted by cornball

nice. Hydrogen becomes a metal at 1.4 megabars!! Would you get that pressure at the bottoms of the oceans?

There's an account of a journey to the deepest part of the ocean from pbs.

On January 23, 1960, the Trieste reached the bottom of the Challenger Deep in the Pacific Ocean's Marianas Trench and set a deep-diving record -- 35,810 feet -- that will likely never be bested. No one has even tried. In fact, in the nearly 40 years since, no person has plunged to within 10,000 feet of the record.....

Less than five hours after they left the surface, Piccard and Walsh touched down onto the floor of the very deepest part of the ocean -- where the crushing pressure exceeds 16,000 pounds per square inch (more than a thousand times greater than the pressure at sea level), and where Piccard reported seeing a fish swimming by. The divers then released the steel shot, and began their rise to the surface.

http://www.pbs.org/wnet/savageseas/d...e-journey.html

16,000 pounds per square inch = 1,100 bar pressure in the deepest ocean depths.

You need pressure more than 1,000 times greater than this for metallic hydrogen.

[firebird]

Just thinking, the deepest ocean depth is 35,810 feet for a pressure of 1,100 bar.

To get metallic hydrogen we need 1.4 million bar, which is 1,273 times more pressure than at the bottom of the ocean.

Therefore if the deepest ocean depth was 35,810 x 1,273 = 4,5586,130 feet deep, we could get metallic hydrogen there.

4,5586,130 feet = 8,634 miles ocean depth for metallic hydrogen.

[shellgirl]

guys, i'm new here and i just wanna say thank you for opening my eyes with very interesting discussion.