4 unbelievable chemical substances humans have discovered

Scientists create and discover new materials all the time. But few are so jaw-droppingly cool that they deserve to be recognized.

From mindbendingly lightweight solids used by NASA to metals that melt in your hand, here are a few of the neatest chemicals around, sourced from this Quora thread.

Aerogel: The lightest solid known to man

This remarkable gel is the world's lightest solid.

Since its invention in 1931 by American scientist Samuel Kistler, it has been used in space missions to collect dust from a comet's tail, by government agencies for developing insulated tents, and even for manufacturing clothing that protects a person from extreme heat.

NASA has nicknamed it "Blue Smoke" because it kind of looks like a hologram.

What makes this substance so cool lies in its seemingly paradoxical properties, Quora user Abhinash Tummala writes. This hard gel is mostly air and therefore extremely lightweight, not unlike a sponge. But it is also very good at repelling heat. As you can see in the image below, it can protect a flower from a strong flame.

The individual molecules that make up aerogel can also act like mini baseball gloves - they can capture fast-moving particles without damaging them. This was really useful during NASA's Stardust mission.

Scientists fashioned silica-based aerogel onto a massive tennis-racket-shaped collector that sat outside its Stardust spacecraft. Its purpose was to capture fragile particle fragments trailing behind the Comet Wild 2 without damaging them. Because aerogel is strong and relatively transparent, scientists were then able to easily find and extract the particles later for analysis.

Aerogel's precursor is structurally similar to Jell-O. The gelatin powder in Jell-O forms a flexible, liquid solution when mixed with warm water, which then cools into a stiff, tangled network that chemically looks like an unruly ball of yarn and sets into a shape. But, if you heated the set Jell-O, it would dry out and you'd be left with a lump of Jell-O powder once again.

Aerogel, on the other hand, isn't made of gelatin but is made from one of a variety of substances, depending upon its desired use. Most commonly it is manufactured from silica, the most abundant mineral in Earth's crust. Unlike the process of making Jell-O, wet aerogel is put through a cycle of pressurized cooling and heating, which makes it retain its shape after drying out.

The resulting aerogel is mostly air, making it still a solid but extremely lightweight. It is often described as feeling like Styrofoam or that flaky, green foam that fake plants are potted in.

You can make your own aerogel by following one of these recipes.

Gallium: The metal that melts at room temperature

As Quora user Xu Beixi? writes, this soft, shimmering solid metal is quite unusual. At low temperatures, it exists as a brittle, hard structure. But when warmed to just above room temperature, it melts into a shiny puddle.

By far its main use has been in the manufacture of smartphones and aerospace and telecommunications industries.

While this chemical element exists in the periodic table, it doesn't occur in nature all that much. Trace amounts can be found in zinc ores and bauxite, which is the main source of aluminum. It does, however, exist on Amazon, where you can buy it for only $10.

If you splurge on some, make sure to keep it away from your iPhone - as it degrades other metals.

This is especially true if the aluminum backing on your phone is scratched, which allows the gallium to penetrate more deeply into the metal lattice. This YouTube video by TechRax demonstrates what happens if you pour melted gallium onto the scratched aluminum backing of an iPhone:

A few hours later, the back of the iPhone had completely decomposed:

Diamond Nanothreads: Possible basis for a space elevator?

This new manmade fiber composed of carbon atoms arranged into a zigzagging structure reminiscent of that of a diamond's may be the strongest, stiffest nanomaterial ever made.

Discovered in 2014, its strength appears to surpass that of carbon nanotubes, which is another ultra-strong and lightweight material.

Shockingly, it is also extremely thin. It measures only three atoms across and is much thinner than a strand of hair.

Since this structure was discovered only recently, its composition must be confirmed with higher resolution images.

Its properties and behavior also need to be understood more deeply before it can be scaled up for use commercially.

But if everything checks out, it's possible that diamond nanothreads could theoretically be strong yet light enough to build an elevator to space. Other candidates, such as steel, would eventually break under their own weight if stretched long enough.

Ferrofluid

This porcupine-like suspension of super-fine magnetic particles - usually iron - is a liquid that begins to dance and form mind-boggling structures after a magnetic field is applied to it, Quora user Richard Tabassi? notes.

Each individual tiny particle in ferrofluid is coated with a surfactant, a chemical that prevents the particles from glomming together, and is suspended in a liquid - water for instance. The particles aren't like the magnets that you stick on your refrigerator. They're what scientists call "paramagnetic," meaning that when they're near a magnetic field, they turn into tiny magnets that move around and stick to other tiny magnets suspended in the field.

Ferrofluid was created in 1963 by NASA scientist Steve Pappell as a prototype for rocket fuel that would propel a spacecraft after a magnetic field was applied to it. The weird thing about ferrofluids is that they behave like both a liquid and a solid at the same time.

This video by YouTuber Ferrofluidvideos shows the stunning shapes and movements that ferrofluid can make when under the influence of magnetism.

You can watch the full video here:

Check out the full Quora thread for more awesome things.

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