I am looking for some guidance in creating a chemical element. I want to know if it is scientifically plausible for a single fictional element to do all the things I need it to, even if at a stretch, and what sort of atomic mass and atomic number it would have? Or if I should just give in and not try to justify it?

The desired end results of this element are giant monsters, giant robots and attracting unwanted attention from space due to radiation signatures. So the necessary features of the element are;

  1. Naturally occurring in the universe, rare though.

  2. Primary source of energy for ecosystems evolved to consume it.

  3. High potential energy output (Both within life evolved to consume it, and when harnessed by humans as a power source).

  4. Capable of creating incredibly strong alloys.

Additional features that would be nice but not necessary;

  1. Radiation produced isn't harmful but detectable.

  2. Said radiation is capable of leaving the Earths atmosphere and being detected in outer space (Given sufficient travel time of course).

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    $\begingroup$ Have you looked at carbon ? It's not rare, though. $\endgroup$
    – Burki
    Jul 12, 2017 at 10:57
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    $\begingroup$ All chemical elements which occur in nature are known. In the first half of the 19th century imagining a fictional naturally-occurring chemical element was possible. Today it is no longer possible. $\endgroup$
    – AlexP
    Jul 12, 2017 at 11:06
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    $\begingroup$ If you say you look for a "fictional" element, just create one? I mean, that's what fictional means. $\endgroup$
    – Fl.pf.
    Jul 12, 2017 at 11:10
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    $\begingroup$ @Miech there are no empty spaces, but it doesn't ever really end, you can just keep adding more protons to get new elements, check out the islands of stability for some theoretical super heavy elements that don't decay in microseconds. $\endgroup$
    – Josh King
    Jul 12, 2017 at 14:18
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    $\begingroup$ @Miech oh yeah, nobody liked star wars, star trek, stargate, firefly, etc pp, because the movies didn't explain how stuff works. Nobody cares about that sort of thing. Nobody cares what kryptonite is. $\endgroup$
    – Fl.pf.
    Jul 12, 2017 at 16:32

5 Answers 5


I would say yes. There's already a real-world element that does at least the first three and its name is uranium.

Naturally occurring in the universe, rare though.

Yep. In fact it's one of the heaviest naturally-occurring elements.

Primary source of energy for ecosystems evolved to consume it.

According to this answer on another question, there are indeed organisms that have evolved to use the radioactive decay of uranium as fuel.

High potential energy output (Both within life evolved to consume it, and when harnessed by humans as a power source).

Yep. The energy density of uranium is ridiculously high compared to stuff like coal, as this graph demonstrates (courtesy of @Michael Kjörling in the comments).

Capable of creating incredibly strong alloys.

I don't know about incredibly strong, but I know that depleted uranium is incredibly dense.

Of course, if you're creating a fictional element, you can easily give it the first three properties, based on uranium, and then handwave #4 and #5 somehow.

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    $\begingroup$ And Uranium even produces non-harmful radiation. That's what they told me at the plant I work anyways. But I'd still argue it wouldn't work as a primary source for energy for an entire ecosystem. $\endgroup$
    – Raditz_35
    Jul 12, 2017 at 11:21
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    $\begingroup$ About the energy density, xkcd to the rescue as always: Log Scale. $\endgroup$
    – user
    Jul 12, 2017 at 12:01
  • $\begingroup$ @Raditz_35 in normal decay, Uranium emits alpha particles which can't penetrate the skin, so are usually harmless. Note that when U-235 is used for nuclear fission (that's the energy generating reactions used in power plants, and bombs...) it's really unhealthy... $\endgroup$
    – G0BLiN
    Jul 13, 2017 at 12:25
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    $\begingroup$ This answer may be improved by expanding on the difference between naturally occurring uranium isotopes, specifically U-235 and U-238 - the former is the fissionable material (used in bombs and reactors), the latter is much more stable, and thanks to its high density is useful for military purposes both for armor and armor piercing weapons. It is also a by-product of uranium enrichment - so the humans/organisms can use enrichment to get both U-235 for energy and U-238 for armor/weapons. Note that both forms are dangerous to humans, though... $\endgroup$
    – G0BLiN
    Jul 13, 2017 at 12:41


Muonium (true muonium) is a theoretical form of matter comprised of a muon and antimuon. Like neutronium and other theoretical forms of normal matter it is not on the periodic table; it would have to go before hydrogen and so have a negative atomic number. Muonium would be your source of muons.

The best speculative fiction leverages real theories. Muons are cool and real and potentially good for lots of things. They also have a very short halflife and so they are hard to get; therein is the fiction. Maybe the interaction of muon and antimuon in muonium stabilizes both so neither can easily decay. Once you have your muonium you can use the muons for muon-catalyzed cold fusion

Muons are heavy cousins of electrons. On replacing an electron in hydrogen, this muon hydrogen can participate in room temperature fusion reactions. Fusion is definitely energetic enough to fulfill points 1,3,5 and 6. Point 5 (radiation detectable but not harmful) is tricky because the earths atmosphere would soak up radioactive emissions not energetic enough to be harmful. But if you move this tech to the Moon or space (in a satellite?) then the helium nuclei produced would definitely be detectable at a distance and give away what was taking place.

In regard to an organism taking advantage of this, that part is tricky. Hydrogen chemistry is within the power of an organism. I worry about an organism being able to capture so much energy at a pop; there is no gradual fusion reaction I think probably the way to do it is to have the fusion reaction absorbed by a chemical reaction - for example something like a heme ring with multiple metal ions that are moved to an energetically unfavorable state by the muon fusion. The metals then revert back to their prior state in an orderly fashion, allowing the energy to be captured gradually at ATP.

Re alloys: I propose muon beryllium. Beryllium alloys are super strong, super light and very pretty. They are real. One can assert that substitution of muonium for beryllium's 2 electrons augments these properties.

  • $\begingroup$ Thank you for this answer. Very interesting stuff and a something for me to look further into. Concerning the points you made about point 5/6, that is what I had planned. If it could only be detectable outside of the Earths atmosphere, then I would put it down to spaceships a Luna based radiation. $\endgroup$ Jul 14, 2017 at 13:49

OP, Say you have a particular "element" as you say (whether carbon, iron, gold or the like). Those elements have a specific number of protons. Each atom (say gold) has a specific number of protons (gold == 79).

BUT the number of neutrons can vary. That's called an isotope. So gold usually has 118 neutrons, but occasionally you can get 116 neutrons and a few other variants.

(Most isotopes are not stable - they just evaporate quickly.)

As someone pointed out, you may be thinking of a "material" or "compound" more than an "element". However, taking your question at face value...

It is no longer possible to discover a "new element" - in short, we have fully found and investigated every one of them. (We can even build some from scratch, which is cool.)

But in a handy-wavey sense, you could say that on planet X there exists an isotope of Iron (or Gold, Carbon - whatever base element you want) which is stable and has the very special properties you mention.

For some reason, the isotope - ultra-iron! - which is unknown to us, and difficult/impossible for us to manufacture in labs - for some reason it appears on your planet X. How could that be? Maybe there was (or still is) a black hole or even something more exotic such as a pulsar, magnetar (!) or even something more fanciful such as a "dark energy concentration" (!!) .. nearby your planet X.

Recall that, in short, "elements" as you ask for are made in stars, so exotic galactic phenomena kind of add up for you.

So, that is a bit more scientific than the usual "Krypton" is a special "thing" that comes from a certain planet - you know?

A challenge now would be to read up on isotopes (and indeed the elements for that matter), and these days you have wikipedia a click away. Maybe it will give you some ideas.

Here's an plot point for you :) ...

So, Your Planet is quite close, let's say 300ly, to the Crab Nebula, which for us is just a pretty dot in the sky. (We are 7000 ly away from the Crab Nebula.)

enter image description here

At that relatively short distance (unknown to our physicists today), the Crab pulsar's spinning neutron star emits huge quantities of neutralinos, which are in real life one of the current subatomic particles, which, our scientists are desperately trying to create or spot. It's extremely difficult/impossible to see neutralinos here, but on Planet Mystere, they are bathed in them. (Neutralinos are indeed harmless to life and matter).

It turns out, a neutralino bath creates a unique stable isotope of Iron. As described in the above answer. So that's why Planet Mystere has the amazing "crab-iron" or "neutralino-iron" or "heavy-iron" as our scientists come to call it. You can build spaceships, AI, and all sorts of wild stuff with neutralino-iron, that cannot be built with what we think of as materials. (Surely, it would be superconducting to begin with, it would form macroscopic single-molecule nano fibers easily, etc etc - naturally!)

But check this out...

As the material moves away from the vicinity of the crab nebula, there are less and less neutralinos, and .... the isotope falls apart and it becomes normal iron again.

So those jokers can build FTL ships, and build true AI - but - as soon as they fly, oh, 100 ly further away from the Crab Nebula - the super-substance just turns in to a lump of iron, rather like a 70s Chevy small block.

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    $\begingroup$ Please be careful if you place the planet near a black hole, pulsar or similar astronomical object. It's far too easy to strain suspension of disbelief well beyond what's reasonable for anyone with even cursory understanding of those phenomena, particularly if you want the planet to be habitable to any kind of life that resembles anything we can envision. (However, don't be afraid to cook up a scenario and ask us if it's realistic!) $\endgroup$
    – user
    Jul 12, 2017 at 14:30
  • $\begingroup$ Hi Michael, good one - sure but TBC what I meant.... I didn't mean "orbiting a black hole" (which, BTW, seems totally possible now). I meant (A) there were black holes in the vicinity when the planet formed or (B) there are black holes nearby in the sense that, Earth is (we don't know) say 1000 ly from the nearest BH, whereas Planet Mystere is merely 5 ly from the nearest BH. That could cause - we'll say - subatomic particles that we struggle to find in the LHC, to be in abundance on Planet Mystere. (Axions! Neutralinos! Higgs!) $\endgroup$
    – Fattie
    Jul 12, 2017 at 14:58
  • $\begingroup$ Regarding pulsars, they are very directional .. in short, the Crab nebula is 7000 ly away, let us say. There is some distance (I don't know what it is - let's say "200 ly") at which the Crab Nebula and it's axion-spewing (!) neutron star would be perfectly safe for life, but amazingly nearby and prominent (since it's 30 ly across, I believe). $\endgroup$
    – Fattie
    Jul 12, 2017 at 15:02
  • $\begingroup$ Even a few lightyears from a black hole would probably cause a pretty much irradiated planet. Please don't take my comment the wrong way; I'm not saying what you propose can't work. I'm just saying be careful with it! $\endgroup$
    – user
    Jul 12, 2017 at 15:03
  • $\begingroup$ hi @MichaelKjörling for sure - no TBC I was thinking like "two hundred ly away". Note - I believe not all BH irradiate, if there's no infall, there's no furnace of hellfire you know? :) $\endgroup$
    – Fattie
    Jul 12, 2017 at 15:17

Hydrogen does all of them except 4 (well, Hydrogen is used in plastics, so you can stretch a bit the definition of alloys...).

It can be oxydized to produce chemical energy, or can be used as nuclear material for fusion reaction. Both use produce radiation (fusion is well visible from far far away...)

Maybe you can consider a compound instead of an element (Cavorite, Thiotimoline are just some example) which can fit your purpose.

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    $\begingroup$ H$_2$ doesn't fit requirement Nr 1. (being rare in the universe), it is quite abundant $\endgroup$
    – Fl.pf.
    Jul 12, 2017 at 11:09
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    $\begingroup$ Carbon fits a lot better than Hydrogen $\endgroup$
    – Separatrix
    Jul 12, 2017 at 11:40
  • $\begingroup$ @Fl.pf. While H$_2$ is rather abundant in the universe, it's not particularly abundant in the atmospheres of the rocky bodies we know of. Gaseous hydrogen is simply too light to remain in the atmosphere for very long, unless your planet has huge gravity. I saw a diagram of this on Wikipedia, and it's been used here on WBSE once or twice that I've seen, but I can't remember exactly where. It graphed ability to retain gases against temperature and gravity, IIRC. $\endgroup$
    – user
    Jul 12, 2017 at 12:04

Chemical elements behave the way they do because their properties are determined mostly by the number of electrons and the way they occupy the shell. Nucleus is very small comparatively to the size of atom (i.e. the size of the electronic shell) and doesn't seem to have other influence than determine the number of electrons to be equal to its number of protons. This means that isotopes of the known elements won't do the job as far as your requirements are concerned.

So it is only by some shameless hand waving you can get your element. One option is to invent a nucleus for your element which is made not of protons and neutrons, but of some "fractional nucleons". The fractional nucleons would contain a number of quarks not divisible by 3. Then, however you'd struggle to complete an electron shell around these nuclei, you would get you particle slightly charged. This charge imbalance would help your particle form strong chemical (ionic) bonds with other elements, but not much with itself, because of the electrostatic repulsion.

You could invent another "fractional element" with which your first element forms an ionic crystal called "thorazine" or whatever Starcraft name you want. The crystal should be very rare, but would be the only known mineral where these fractional atoms are found in large enough quantities.

One way to deal with the source of energy issue is to make this thorazine stable both in amorphous and crystalline state. A lot of thorazine comes from meteor impacts and much of it is amorphous. But one can induce the transition by applying large pressure, or heating a little the mineral. As it stands, the ground state is crystalline, so there should be a lot of heat from the transition.

If, on the other hand, one needs some radiation, we could make the thorazine unstable under certain conditions like the presence of a neutron flux.


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