Why is Helium so difficult to synthesize?


Why is Helium so difficult to synthesize?

In: 74

Noble gasses don’t like to react with things. So finding it around as compounds is hard.

The only way we can get it is through finding it as itself.

It’s a noble gas so it doesn’t interact with anything so it’s not found in many molecules that it can be liberated from.

Helium synthesis cannot be done using chemistry, because helium is an element and not a chemical compound. Elements are defined by the number of protons in their nuclei, and you can’t modify an atomic nucleus without a nuclear reaction. You need some type of reactor that fuses hydrogen nuclei together to form helium, typically using an insanely strong magnetic field that consumes as much power as a small city—and the amount of helium synthesized is so small it’d be difficult to even measure, let alone put to practical use.

No element is easy to synthesize. Changing one element to another requires nuclear reactions, and nuclear reactions that aren’t very slow have mostly already happened.

When we harvest other elements, we’re not actually creating atoms of that element. We’re just taking them out of molecules in which those atoms already existed. For example, iron can be found as oxide minerals, with chemical formulas along the lines of Fe2O3 or FeO or the like (you know these particular minerals as “rust”). When we refine these compounds into pure iron, all we’re doing is separating the iron from the oxygen it’s bonded to.

But helium doesn’t naturally bond to anything. You have to really, REALLY try to get any sort of bond with helium at all under anything resembling normal Earth conditions, and even then the resulting compounds are wildly unstable (much too unstable to exist naturally). So all helium on Earth exists as just regular old free gaseous helium.

If helium were a heavy enough element, that wouldn’t be a problem. It’d hang around in the Earth’s atmosphere, and we could distill it out by cooling down air, like we can do with oxygen, nitrogen, argon, and other major components of the atmosphere. But helium is too light for the Earth’s gravity to hold onto it at the temperatures of Earth’s atmosphere, so any helium in Earth’s atmosphere quickly escapes into space. (If you’re wondering how this works: basically, the random jostlings of gas atoms against one another is likely, over the span of years, to kick a helium atom up to escape velocity.)

So the only place we can get helium is from underground, where it’s trapped and can’t mix with the atmosphere. Currently, we do this mostly from natural gas deposits, but those are rapidly running low, and we’re depleting the Earth’s supply of helium with them. (Helium is naturally produced during nuclear reactions, but only very slowly, so helium is functionally non-renewable on human timescales.)

It’s impossible to synthesize because to synthesize means to combine two things to create something new. Helium is an element, so to make an element you have to combine protons and neutrons which is much much harder than it sounds.

There are only 2 environments that commonly make elements. First is inside stars where the pressure and heat are unimaginably high that the protons and neutrons flu around in massive soup until they can stick to each other. That’s pretty impossible to replicate at this point.

The second is radioactive decay where unstable atoms lose protons and neutrons in order to become more stable. That is actually the only reason why we have any useable amounts of helium on earth to begin with. Radioactive elements deep in the earth decayed and created helium over billions of years. Which of course that time scale is just so insanely long that it really isn’t useful to wait until radioactive elements decay into more helium.