How Does Gallium Work?

Gallium is super rare, really useful in LEDs and smartphones, and will melt in your hand -- but won't boil until it hits 4000 degrees Fahrenheit. Learn more in this episode of BrainStuff, based on this article: https://science.howstuffworks.com/gallium.htm

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff, a production of iHeart Radio, Hey
Brainstuff Lauren Bolg bomb here. Gallium is a rare, silvery
white element that can pull off one of the coolest
parlor tricks on the periodic table. At room temperature, gallium
is a shiny metallic solid that resembles pure aluminum. But

(00:23):
hold it in your hands for a few minutes and
this solid hunk of metal starts to melt. The melting
point of gallium is just eighty five point six degrees fahrenheit.
That's twenty nine point eight celsius, which means that it
melts into a mirror like puddle in your hot little hand.
In its liquid form, gallium looks a lot like mercury,

(00:43):
but gallium isn't toxic like mercury, so it's safer to handle,
though it can stain your skin. But gallium is so
much more than fodder for melt in your hand YouTube videos.
It's also a key ingredient in LED lights and the
go to semi condu after material for the powerful microchips
in your smartphone. The only thing stopping gallium from taking

(01:06):
over the electronics world is that it's very rare and
very expensive compared to silicon. Pure gallium doesn't exist in
its shiny elemental form in nature. It needs to be
extracted from minerals like box site through a multi step
chemical process. According to the U S Geological Survey, the
abundance of gallium in Earth's crust is a measly nineteen

(01:28):
parts per million. The silicon, by comparison, is two d
and eighty two thousand parts per million. In the year
eighteen fifty seven, a French chemist was the first person
to isolate and recognize gallium as a new element. He
named it after the Latin name for France, Gallia. But
four years before that, Russian chemist Dmitri mend to Leave

(01:52):
predictive gallium's existence. Mend to Leave, known as the father
of the periodic table, saw that there was a gap
in the table after aluminum, so he posited that a
missing element would share many of the properties of aluminum,
but with a different atomic structure. Amanda Leave was right,
but he couldn't have predicted how gallium's unusual qualities somewhere

(02:14):
between a metal and a non metal, would make it
ideal for modern electronics. Here's another cool and somewhat bizarre
fact about gallium. While it melts that the aforementioned hand temperature,
it doesn't boil until it reaches over a scorching four
thousand degrees fahrenheit or two thousand degrees celsius. It's exact

(02:37):
boiling point is listed differently in different chemistry texts, and
I'm not going to check it personally today, so that's
the ballpark. At any rate. This earns gallium the award
for maintaining the longest liquid phase of any element. So
why is this for? The article this episode is based on.

(02:57):
Has to Works reached out to the American Chemical Society
and spoke with Daniel Mandiola, a chemistry professor at the
University of Pennsylvania. He said, gallium is confused. It melts
at a low temperature, which is consistent with a light element,
but it boils at a very high temperature, which is
consistent with a very heavy element. Gallium doesn't know if

(03:17):
it wants to be a metal or a non metal.
Gallium's dual personality stems from where it sits on the
periodic table among two groups called the metalloids and the
post transition metals. Gallium is next in line after aluminum,
but it's atoms are far more independent than its shiny
foil uh. Also, aluminum is more electro positive trait of

(03:42):
true metals. That means it's more apt to release electrons
Like silicon. Gallium is a good conductor of electricity, but
not a great one. That's what makes both of these
metalloids prime candidates for semiconductors where the flow of electricity
needs to be control but using current manufacturing processes, A

(04:03):
wafer of gallium arsenide, the most popular gallium based semiconductor material,
is roughly a thousand times more expensive than the silicon
wafer because of gallium's rarity. Even though gallium is that
much more expensive than silicon, it's become a popular semiconductor
material in the latest generations of smartphones. Smartphones communicate with

(04:26):
cellular data networks using radio frequency chips or r F chips,
and r F chips made with gallium arsenide give off
less heat than silicon and can operate at higher frequency bands,
a requirement for five G networks. A little more than
of all the gallium consumed in the United States is
used to make r F chips and other types of

(04:47):
integrated circuits. However, one of the coolest applications of gallium
is in light emitting diodes, or l eds, which are
now used in everything from computer displays to traffic lights
to car headlights. L e d s are so popular
because they're super efficient they don't heat up. The first
visible light l eds were invented in the early nineteen

(05:09):
sixties when researchers at General Electric discovered the unique properties
of diodes made with various gallium alloys, that is, combinations
of gallium with arsenic, nitrogen, phosphorus, and other elements. In
a diode, electrons move through two layers of semiconductor material,
one with a positive charge and the other with a

(05:29):
negative charge. As free electrons from the negative side fill
holes in the positive side, they emit a photon of
light as a byproduct. Scientists have discovered that different gallium
alloys emit photons of different visible light frequencies. So gallium
arsenide and gallium phosphide produced red, orange, and yellow light,

(05:51):
while gallium nitride produces blue light. And not only do
l e d s produced light when connected to electricity,
but the process can be reversed. The special diodes inside
of solar cells are also made of galleum based semiconductors.
They take incoming light and separate it into free electrons

(06:11):
and holes, a generating voltage that can be saved in
a battery as electricity. The aerospace industry has been hot
on gallium for decades. All of the high end solar
panels that power satellites and long range spacecraft are made
with gallium arsenide, including the critical solar panels on the
Mars Exploration Rovers. At peak performance, the galleum based solar

(06:35):
cells on the Mars Rovers could produce nine hundred watt
hours of energy per martian day. But wait, there's more.
A Mendiola said. Medicine is beginning to use gallium too,
for detecting and treating certain types of cancers. Gallium sixty
seven is attracted to cells that replicate faster than normal,

(06:55):
which is what happens in a tumor. Gallium sixty seven
as a radioactive isotope of gallium that emits non toxic
gamma rays. A Radiologists can scan a patient's whole body
for tumors or inflammation from an infection by injecting gallium
sixty seven into their bloodstream. Because gallium sixty seven binds

(07:16):
to clumps, of fast growing cells. Those potential trouble spots
will then show up on a scan that's sensitive to
gamma rays. Gallium nitrate has also shown effectiveness in shrinking
and killing certain types of tumors, not just detecting them.
Today's episode is based on the article gallium boiled four

(07:39):
thousand and forty four degrees fahrenheit but will also melt
in your hand on how staff works dot Com. Written
by Dave Ruse. Brain Stuff is productive i Heart Radio
in partnership with how stuff works dot Com and it's
produced by Tyler Clang. Four more podcasts from my heart Radio.
Visit the iHeart Radio app, Apple Podcasts, or wherever you
listen to your favorite shows.