# Talk:Metallic hydrogen

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## Comment

I think that a lot of theoretical confusion could be cleared-up by including a phase diagram as in the original article. 67.126.176.69 (talk) 22:04, 29 January 2017 (UTC)

Adapted from an writeup for Everything2.com

The Law of Charles and Gay-Lussac is not applicable here because we're far from an ideal gas. Removed. 193.171.121.30 00:22, 6 Dec 2004 (UTC)

Isn't metallic hydrogen an allotrope of hydrogen? If so, it seems like that ought to be mentioned in the article... TerraFrost 02:59, 27 Feb 2005 (UTC)

Solid metallic hydrogen at room temperature (if possible) would not be useful for making lightweight cars! It would be extremely reactive, like other group I metals. It would likely burst into flames upon contact with air. Unagiflum 01:28, 13 Mar 2005 (UTC)

Yes, it would. Lithium barely rusts or burns because it's so hard, or maybe its -O layer makes it so, and the hardest alkali metals are in the first rows. Hudrogen has a sudden jump in atomic size going to lithium compared with the later alkalis, so it should make a stiff aluminoid metal. lysdexia 04:49, 5 November 2005 (UTC)
Kinda correct, but there's an obvious flaw. Hydrogen oxide is a liquid at room temperature. GeeJo (t) (c)  14:19, 11 February 2006 (UTC)
Boron has no oxide layer; it's the smallest, densest fuel-atom, and doesn't burn at normal conditions because of its great self-bonding barrier. So solid hudrogen would be its analòg. -lysdexia 13:00, 10 October 2007 (UTC) —Preceding unsigned comment added by 68.123.4.253 (talk)
But metallic hydrogen would be quite noble (doesn't react with water or nonoxidising acids)? Maybe it would be extremely flammable in air, but not in water (if it doesn't transform into gaseous H2)? --83.100.0.21 (talk) 13:21, 23 December 2008 (UTC)

There seems to be undefined here just what is being talked about. Do we assume that Hydogen, presumably as Hydrogen molecules when first pressurized, somehow reverts to Hydrogen atoms to become a "metal?" This appears a flaw in the entire discussion. It would seem possible that under high pressure, molecular Hydrogen could be forced into a lattice which would consist of HHH+ and H- units, both of which are known species, and this lattice would be expected to be a good conductor...The assumption appears to be that if such a lattice were formed it would undergo further degeneration to a metallic structure of free electrons and protons.64.68.162.60 (talk) Dean L. Sinclair 25 Aug. 2010 —Preceding undated comment added 20:58, 25 August 2010 (UTC).

I have a question that I would love answered. There is talk in here article about Hydrogen permeation of metals and alloys. Is there an alloy of Hydrogen and Titanium? From my knowledge of alloys I know that copper is added to aluminum to improve properties. Could metallic hydrogen be alloyed to titanium? Also could the necessary force required be generated in a reactor? What does nuclear physics have to say about this holy grail of hydrogen metal? — Preceding unsigned comment added by 69.165.169.141 (talk) 00:56, 28 April 2013 (UTC)

## Diamond is not stable.

Graphite is a more stable form of carbon than diamond. The decay period for diamonds is just very long. This should be clarified within the article, for completeness' sake.

Furthermore, the article's discussion on a car made from metastable metallic hydrogen is internally inconsistent. The article says that it can be used as a material for making cars and also burns very cleanly and energetically. These seem to be mutually inconsistent things. (Although aluminum has structural uses and is a good fuel--for rockets--there is a layer of aluminum oxide that prevents aluminum from spontaneously combusting in the air. Such a protective layer would not form for metallic hydrogen, because oxidizing it would probably yield water and energy.)

Neither do the paraffins have protective layers. lysdexia 04:49, 5 November 2005 (UTC)

## Present in planetary cores?

I'm wondering...I've always seen this as "we think/some scientists believe" that metallic hydrogen shows up, and as the article doesn't cite any sources, I'm not sure if that's a valid statement. Should that be changed?

The atmospheric pressure of Jupiter is less than Earth's, and since it doesn't exist on Earth, I can't see why it would exist on Jupiter. Until we get a citation for this, it should be removed.

Pressures on Jupiter range from far below Earth atmosphere (at high altitude) to millions of atmospheres (near the core). The astrophysicists are referring to the core areas, where pressure and temperature are more than high enough to make the hydrogen metallic. --Nbishop 01:46, 14 February 2007 (UTC)

## Superconductivity

One of the links given in the superconductivity section isn't even about metallic hydrogen, it is about magnesium diboride. I'm removing it. [1]. Also, I'm adding a link to the original paper by Ashcroft so that those with access to the journal can read it. --Nbishop 01:46, 14 February 2007 (UTC)

Here is some news: http://www.ciw.edu/superconducting_hydrogen V (talk) 19:55, 1 February 2010 (UTC)

## electron wavelength?

Hi! I'm just visiting from german wikipedia, where I just read the same thing: the spacing is more comparable with an electron wavelength (see De Broglie wavelength). What is that supposed to mean? The wavelength depends on momentum, so what is the wavelength. It's like talking about the wavelength of a photon, which is obviously nonsense. Is it maybe the Compton wavelength? CWitte 09:54, 27 July 2007 (UTC)

I agree. This has to be removed. De Broglie wavelength of the electron with Rydberg-like energy is of the order of Bohr radius. Compton wavelength, on the other hand, is way too small. --144.92.110.139 (talk) 00:36, 2 September 2008 (UTC)

## check these references

Nergaal (talk) 11:34, 11 December 2007 (UTC)

The structure of this page looks a whole lot like http://www.chemie.de/lexikon/e/Metallic_hydrogen to me. Robbiemuffin (talk) 00:19, 3 March 2008 (UTC)

Maybe that's because it is copied from Wikipedia under the terms of the GNU license, as noted at the bottom of the page. Sakkura (talk) 01:54, 25 July 2008 (UTC)

## Density of metallic hydrogen.

Perhaps it would make sense to put the actual value of the density of the subject, rather than simply stating it is 9 times denser than the more common allotrope. To be honest, I want this as a convenience for myself so I don't have to keep googling it, taking forever to get the actual value. Granted, if we decide to give one number regarding the material's properties, it makes sense to give other important property values in the article. —Preceding unsigned comment added by 76.176.170.232 (talk) 01:30, 28 July 2008 (UTC)

Density depends on conditions, such as pressure and temperature. Since metallic hydrogen only forms under extreme conditions of very high pressures and temperatures, there is no real standard density to provide. Sakkura (talk) 00:51, 30 July 2008 (UTC)
of course the density is variable under changing pressure so can we clarify this "9 times denser" business?9 times at the same pressure compared to liquid/compressed gas hydrogen that has not yet under gone phase shifting at even higher pressures to form a temporary metal? —Preceding unsigned comment added by 118.208.23.79 (talk) 07:52, 28 May 2009 (UTC)
The issue does not seem to be solved yet. What is "9 times denser than standard hydrogen"? Hydrogen under standart atmospheric conditions? I can't imagin that. Liquid hydrogen? It is true that density depends on conditions. But the current wording does not take that into account either and does not seem usefull. Does anyone have any numbers for any specific conditions? Thus both, density and conditions could be named in the article just to have anything. --GlaMax (talk) 09:53, 15 December 2009 (UTC)

## Artificially metallic hydrogen?

Could one make hydrogen conductive at normal temperatures and pressures by simply irradiating it with 15eV UV light of high enough intensity such that a significant number of the electrons are promoted to the conductance band? John Eastmond (talk) 23:13, 5 Nov 2008 (UTC)

An idea similar to that was posted several years ago here: http://www.halfbakery.com/idea/Metallic_20Hydrogen#1083949200 V (talk) 17:08, 6 February 2009 (UTC)

## Confusing part of a sentence

In the liquid metallic hydrogen section:

"...which at normal conditions is a liquid even at lowest temperatures..."

What does this intend to say, and can we say it more clearly? Huw Powell (talk) 03:37, 7 December 2008 (UTC)

## Sentence not needed

"Though topping the Periodic Table's alkali metal column, hydrogen is not, under ordinary conditions, an alkali metal. In 1935, however"

I would like to remove this sentence, it is stupid. Hydrogen is far more commonly put on the top of the halogens, but looks nicer on top of group one. This statement proves nothing and makes no point. —Preceding unsigned comment added by 82.2.222.210 (talk) 22:22, 9 December 2008 (UTC)

I once saw a periodic table where hydrogen was in both places. Above the alkali metals because it like them has the first electron of an electron-shell. Also, hydrogen can be a "donor" of that electron (see hydrogen fluoride). Above the halogens because it like them has the penultimate number of electrons in that electron-shell. Also, hydrogen can be an "acceptor" of an electron to complete its shell (see lithium hydride). V (talk) 17:12, 6 February 2009 (UTC)

## Regarding Hydrogen as a Alloying substance

The subsection of the article, "hydrogen permeation of metals" could use some extra supporting evidence or argument. I have here an argument that may be OR. However, if something makes "easy" sense, Wikipedia relaxes the OR rules. Obvious logic does not qualify for the OR label.

The last comment at the first link indicates that hydrogen can fail to permeate things that helium, a smaller particle, can permeate. The second link is all about calibrating helium permeation measurement tools, and it is to be noted that metal is not used, as a thing through which helium permeation is measured.

Now back to a metal like palladium, which hydrogen permeates easily. If we accept the implication that helium cannot permeate palladium (more data supporting that posted after these paragraphs), then we are left with the Question of, "How does hydrogen gas (bigger than helium) do it?" A very simple answer would be that hydrogen atoms are able to give away their electrons into the metallic conduction band of the palladium. That is the essence of "forming an alloy" --but the point here is, hydrogen only has one electron to its name. If it is given away, then the thing left behind is the extraordinarily tiny hydrogen nucleus, which could obviously be expected to permeate practically anything, certainly a block of solid palladium metal. Having done that, the hydrogen could take its electron back from the metal's conduction band, and re-enter the surrounding air. Since helium atoms like to hold on to their electrons tightly, whole helium atoms bounce off of palladium, instead of permeating into it.

How could the essence of the preceding be incorporated into the article? V (talk) 22:22, 5 February 2009 (UTC)

Here's another link: http://www.freepatentsonline.com/6103028.html --This one describes a palladium alloy used to filter hydrogen (by permeation), and includes the sentence: "The helium permeation values of both the sample and the control were undetectable (<0.1 cc/cm 2 -min)." V (talk) 22:31, 5 February 2009 (UTC)

## Metallic hydrogen in literature

Has there been any mention of metallic hydrogen in science fiction? If there has, maybe somebody could add a paragraph or two to the main article? 216.99.198.184 (talk) 22:34, 25 August 2009 (UTC)

## Eclipse Phase

"In the role-playing game Eclipse Phase, metallic hydrogen is mentioned as a spacecraft propellant, especially for landing on planetary bodies and short range orbital transfers.[citation needed]"

I note via Google that there are two pages on eclipsephase.com that use the term, but they are in a forum format, so I don't know if that would count as a proper reference... -- Limulus (talk) 16:56, 2 January 2010 (UTC)

## Introduction Fixed

I just finished a course on solid state chemistry and stumbled across this article. Upon reading the first paragraph I was shocked at it's apparent inaccuracy. Just to be sure I did a bit of math and found that the radius of an electron's orbital can only take on discrete energy levels

Assuming the classical bohr model, it's ${\displaystyle r_{n}={\frac {n^{2}\hbar ^{2}4\pi \epsilon _{0}}{Z|q_{1}q_{2}|m_{e}}}}$ to be exact.

since it's angular momentum only occurs in intervals of h-bar. Albeit, these energy levels are more like probability clouds according to the wave equation and there are also relativistic quantum effects that slightly disturb this. This fact is also evidenced in atomic spectra. Truth be told, hydrogen would collapse rather do what was described in the previous edit. Anyways, I went looking for a paper on the theoretical predictions of metallic hydrogen just to really be sure I knew what I was talking about. Lone behold, I was correct.

Anthonyisageek (talk) 10:26, 19 January 2013 (UTC)

Well, the lead was a mess, because per WP:LEAD it is supposed to summarize the article, which it did not. This is a difficult topic, so please think twice before writing on it. Three glaring problems: (i) Bohr model is inapplicable because of strong interatomic interaction in the highly compressed state, i.e. you can't use single-atom models. (ii) Your version of the lead mixes up solid hydrogen and metallic hydrogen, perhaps because the article you use as reference deals with solid hydrogen and only partly concerns metallic hydrogen. (iii) Grammar. Materialscientist (talk) 10:59, 19 January 2013 (UTC)

## Hydrogen permeation of metals

This seems like speculation- apart from wikipedia does it say anywhere referenceable that hydrides may be considered to be alloys of metallic hydrogen?Axiosaurus (talk) 17:34, 28 October 2013 (UTC)

## Nature published some skepticism of the recently published observation

And they have some citations to look at too:

http://www.nature.com/news/physicists-doubt-bold-report-of-metallic-hydrogen-1.21379

BrianPansky (talk) 06:34, 27 January 2017 (UTC)

I've now added an {{NPOV}} tag to the top of this article: we need to report all of this in a way that follows the guidelines. -- 10:03, 27 January 2017 (UTC)
We need to be careful editing this article: I've just reverted this edit, which seemed to me to be unhelpful, to say the least. -- The Anome (talk) 10:12, 27 January 2017 (UTC)
It is not Wikipedia's job to adjudicate in scientific disputes. Science has published a paper saying it's been observed; Nature has published a report saying other scientists regard this claim skeptically. This is what we should report: our job is not to weigh the evidence ourselves here. Please see the WP:NPOV policy for more details on this. -- The Anome (talk) 10:22, 27 January 2017 (UTC)

## What makes a metal anyways?

I think this article would be more helpful to the non-specialist if it explained what makes a metal in the first place (atoms bonded in a lattice with a pool of delocalized electrons that are free to conduct? something like that). And why it was suspected that hydrogen might be able to solidify into this kind of structure too (and if so, what kind of lattice structure? It would be a naked proton lattice with delocalized electrons, which is surely quite different from a cation lattice where nuclei are swathed in loads of core electrons?). Currently, the article only provided the rationale "hygrogen is at the top of the alkali metals column in the periodic table", which is ass backwards: elements originally got placed in appropriate columns on the basis of their properties, not the other way round. Hydrogen was only (usually) plonked there for tidyness--feline1 (talk) 11:00, 30 January 2017 (UTC)

I made a few changes to the "Metallization of hydrogen under pressure" section along these lines, although it would perhaps benefit from a little more rigour...--feline1 (talk) 11:21, 30 January 2017 (UTC)

## Helium-4

From "Theoretical predictions", subsection "Liquid metallic hydrogen": "Helium-4 is a liquid at normal pressure near absolute zero, a consequence of its high zero-point energy (ZPE)." Is this supposed to be helium-4? It is unclear what the relevance of helium-4 is. I am unable to view the references. Axl ¤ [Talk] 13:13, 30 January 2017 (UTC)

## Semi-protected edit request on 31 January 2017

REQUEST: Additional information for the Liquid Metallic Hydrogen:

SPECIFIC DESCRIPTION: Ab initio calculations have predicted that, at very high pressures and temperatures, liquid metallic hydrogen can dissolve iron, silica, magnesia and water ice [1,2,3,4], showing that the rocky core of giant planets, like Jupiter, may be dissolving.

1. Wahl, S. M., Wilson, H. F. & Militzer, B. Solubility of Iron in Metallic Hydrogen and Stability of Dense Cores in Giant Planets. Astrophys. J. 773, 95 (2013). 2. González-Cataldo, F., Wilson, H. F. & Militzer, B. Ab Initio Free Energy Calculations of the Solubility of Silica in Metallic Hydrogen and Application To Giant Planet Cores. Astrophys. J. 787, 79 (2014). 3. Wilson, H. F. & Militzer, B. Rocky Core Solubility in Jupiter and Giant Exoplanets. Phys. Rev. Lett. 108, 111101 (2012). 4. Wilson, H. F. & Militzer, B. Solubility of Water Ice in Metallic Hydrogen: Consequences for Core Erosion in Gas Giant Planets. Astrophys. J. 745, 54 (2012). Fgonzcat (talk) 06:15, 31 January 2017 (UTC)

Too bad all by the same group of authors. Isambard Kingdom (talk) 08:05, 31 January 2017 (UTC)
Not done: it's not clear what changes you want to be made. Please mention the specific changes in a "change X to Y" format.  B E C K Y S A Y L E 06:25, 3 February 2017 (UTC)