Basic Information
To form our bodies and our biochemistry, we humans use molecules based on carbon, as organic molecules are flexible enough to make the complex structures of life. Very few elements can support the variety of molecules that carbon makes. Most speculation about alien biology and exotic life assumes that organic chemistry will be used, as more is known about organic chemistry and it is already known that it can support life. Boron is another element that may be able to make complex structures when combined with other elements, although it is much less common than carbon. It has been suggested as a possibility for alien biochemistry.
Many boron compounds have very similar structures to carbon molecules. Boron is just to the left of carbon, and combined with an element to the very right, such as nitrogen, phosphorus or arsenic, it makes analogous structures. Borazine is a ring with alternate boron and nitrogen atoms, which is similar to the simplest aromatic hydrocarbon, benzene. It is a clear liquid that decomposes in water, and can be made into an inorganic polymer known as polyborazylene. There is a synthetic material, boron nitride, with similar properties and uses to carbon graphite. There are clusters of boron linked by hydrogen atoms known as boranes, which ignite with a green flame with oxygen and may be used as aircraft fuel. There are a variety of compounds that contain both carbon and boron, as well.
A variety of different metabolisms and solvents could be used by Boron-based life. They may be able to breathe oxygen and drink water, excreting a mixture of acids as wastes. However, many boranes and boron-nitrogen compounds are unstable in water, so it may be worth looking into Ammonia As A Biological Solvent if you are interested in boron-based life.
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Game and Story Use
- The use of boron for pyrotechnics means we should expect boron-based 'firewood' and 'coal' to burn violently and make vivid green fires. So the equivalent of a "forest" on a world where life is boron-based could be quite an exciting place.
- As rotting matter decomposes, it may emit boranes that ignite spontaneously into green sparks upon contact with oxygen.
- In general, most boron-based equivalents of organic compounds are highly volatile.
- The atmosphere of a world where Boron-based Life evolved is likely to have a chemical composition that reduces the volatility of boron-based compounds. Such an atmosphere would definitely improve the survival odds of boron lifeforms, possibly giving it a leg up over any carbon-based competitors. So maybe it's not all fireworks on the boron homeworld…
- …but once you transplant that boron lifeform into the oxygen-rich atmosphere of any human habitat, things will get exciting again. A boron lifeform may have offensive weaponry on earth that it lacks on home, or might blow itself to smithereens if it burps. There is plausible room for hilarity or a crisis to ensue, depending on the tone of your campaign.
- There are some real-world polymers that alternate boron and silicon in the same molecular formation. Silly Putty, for example, is made of boron, silicon and oxygen. So it may be worth checking out the silicon-based life page for more ideas.