This is gallium.
It's a metal but it has a melting point of 29.76 degrees Celcius.
Which means that it will melt in your hand
to produce a beautiful silvery liquid like. this
Unlike mercury, which is toxic, gallium is completely safe
which means you can do some pretty amazing stuff with it.
Like mold it into shapes...
or just swirl it around for hours in slow motion
Which we did.
A really cool thing we can do with gallium involves aluminium
I've got an empty aluminium drinks can, which we have sanded all the paint off of,
and some liquid gallium here
Now applying a small drop of this to the aluminium
is gonna do something really interesting.
Onto the can and then
because there'll be a layer of aluminium oxide on the top
just scratch away a little bit...
Now we just need to leave the gallium on there for a few hours
but you can see already that the gallium is tarnishing
from a silvery colour to blackish gray coloor
So this is our can that we left overnight
and you can see that the gallium has spread through the aluminium
and watch what happens when I put my finger through it
So it's incredibly weak it's a really weird feeling
it's it's almost like there's nothing there at all, it just crumbles to
something that feels a bit like ash in between my fingers
And of course we also wanted to give this a try with a full can
just to see what would happen...
[CAN EXPLODES]
Wow! [LAUGHTER]
That way really fast right?
So we've just sprayed gallium all over our faces and the camera
and exploded this because
it took way less time than we thought it was going to.
I thought that might take
up to an hour the quickest and it took seconds there
and it's just exploded in our faces,
really amazingly torn open the can as well.
Exciting and just a little bit frightening.
So what's going on here to change aluminium from something
relatively strong that can be bent and deformed without breaking
to something much weaker and brittle even?
Well contrary to what you might think, it's not a chemical reaction.
The liquid gallium is actually physically penetrating through the aluminium.
It's a process called liquid metal embrittlement.
This is how it works.
As a solid aluminium has a crystal structure.
Its atoms are arranged in a rigid lattice like this,
it's very ordered and the bonds between the atoms are very strong.
As in all metals, the outer electrons of the aluminium atoms
aren't bound to one atom, but instead can move freely within the lattice
It's the attraction between the positive aluminium ions
and the free moving negative electrons
that bonds the crystal together.
But the solid aluminium isn't just one huge crystal.
We can represent the structure in two dimensions.
It's actually made up of many tiny crystals in different orientations
called grains, between the grains we have grain boundaries
there's still some bonding between the grains
but it's not as strong as within the grains themselves
When we introduced just a small amount of gallium
onto the surface of the can, because the gallium is a liquid
it can penetrate very rapidly into the aluminium grain boundaries
and once it's there it gets in the way of the bonding between those grains
This makes it much easier to break the grains apart,
because now instead of pulling on strong aluminium bonds
you're pulling on the weak bonds between the liquid gallium atoms
So it doesn't take much for the aluminium to crumble apart
[LAUGHTER]
That's it for this video, thanks for watching
One last thing a bit of a mystery that we had actually,
we showed you one of the cans exploding as we applied some gallium to it earlier
but to be truthful that was the only time we got a can to explode
every other time we tried we just got a weak little stream
of drink squeezing out of the can
Ah what?
That was not it again. That was it again!
So if you've got any ideas what was happening
that was different that one time the can exploded please let us know
down in the comments
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