WEBVTT - How Does Gallium Work?

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<v Speaker 1>Welcome to brain Stuff, a production of iHeart Radio, Hey

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<v Speaker 1>Brainstuff Lauren Bolg bomb here. Gallium is a rare, silvery

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<v Speaker 1>white element that can pull off one of the coolest

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<v Speaker 1>parlor tricks on the periodic table. At room temperature, gallium

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<v Speaker 1>is a shiny metallic solid that resembles pure aluminum. But

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<v Speaker 1>hold it in your hands for a few minutes and

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<v Speaker 1>this solid hunk of metal starts to melt. The melting

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<v Speaker 1>point of gallium is just eighty five point six degrees fahrenheit.

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<v Speaker 1>That's twenty nine point eight celsius, which means that it

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<v Speaker 1>melts into a mirror like puddle in your hot little hand.

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<v Speaker 1>In its liquid form, gallium looks a lot like mercury,

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<v Speaker 1>but gallium isn't toxic like mercury, so it's safer to handle,

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<v Speaker 1>though it can stain your skin. But gallium is so

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<v Speaker 1>much more than fodder for melt in your hand YouTube videos.

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<v Speaker 1>It's also a key ingredient in LED lights and the

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<v Speaker 1>go to semi condu after material for the powerful microchips

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<v Speaker 1>in your smartphone. The only thing stopping gallium from taking

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<v Speaker 1>over the electronics world is that it's very rare and

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<v Speaker 1>very expensive compared to silicon. Pure gallium doesn't exist in

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<v Speaker 1>its shiny elemental form in nature. It needs to be

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<v Speaker 1>extracted from minerals like box site through a multi step

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<v Speaker 1>chemical process. According to the U S Geological Survey, the

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<v Speaker 1>abundance of gallium in Earth's crust is a measly nineteen

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<v Speaker 1>parts per million. The silicon, by comparison, is two d

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<v Speaker 1>and eighty two thousand parts per million. In the year

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<v Speaker 1>eighteen fifty seven, a French chemist was the first person

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<v Speaker 1>to isolate and recognize gallium as a new element. He

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<v Speaker 1>named it after the Latin name for France, Gallia. But

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<v Speaker 1>four years before that, Russian chemist Dmitri mend to Leave

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<v Speaker 1>predictive gallium's existence. Mend to Leave, known as the father

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<v Speaker 1>of the periodic table, saw that there was a gap

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<v Speaker 1>in the table after aluminum, so he posited that a

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<v Speaker 1>missing element would share many of the properties of aluminum,

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<v Speaker 1>but with a different atomic structure. Amanda Leave was right,

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<v Speaker 1>but he couldn't have predicted how gallium's unusual qualities somewhere

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<v Speaker 1>between a metal and a non metal, would make it

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<v Speaker 1>ideal for modern electronics. Here's another cool and somewhat bizarre

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<v Speaker 1>fact about gallium. While it melts that the aforementioned hand temperature,

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<v Speaker 1>it doesn't boil until it reaches over a scorching four

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<v Speaker 1>thousand degrees fahrenheit or two thousand degrees celsius. It's exact

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<v Speaker 1>boiling point is listed differently in different chemistry texts, and

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<v Speaker 1>I'm not going to check it personally today, so that's

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<v Speaker 1>the ballpark. At any rate. This earns gallium the award

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<v Speaker 1>for maintaining the longest liquid phase of any element. So

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<v Speaker 1>why is this for? The article this episode is based on.

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<v Speaker 1>Has to Works reached out to the American Chemical Society

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<v Speaker 1>and spoke with Daniel Mandiola, a chemistry professor at the

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<v Speaker 1>University of Pennsylvania. He said, gallium is confused. It melts

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<v Speaker 1>at a low temperature, which is consistent with a light element,

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<v Speaker 1>but it boils at a very high temperature, which is

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<v Speaker 1>consistent with a very heavy element. Gallium doesn't know if

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<v Speaker 1>it wants to be a metal or a non metal.

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<v Speaker 1>Gallium's dual personality stems from where it sits on the

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<v Speaker 1>periodic table among two groups called the metalloids and the

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<v Speaker 1>post transition metals. Gallium is next in line after aluminum,

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<v Speaker 1>but it's atoms are far more independent than its shiny

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<v Speaker 1>foil uh. Also, aluminum is more electro positive trait of

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<v Speaker 1>true metals. That means it's more apt to release electrons

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<v Speaker 1>Like silicon. Gallium is a good conductor of electricity, but

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<v Speaker 1>not a great one. That's what makes both of these

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<v Speaker 1>metalloids prime candidates for semiconductors where the flow of electricity

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<v Speaker 1>needs to be control but using current manufacturing processes, A

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<v Speaker 1>wafer of gallium arsenide, the most popular gallium based semiconductor material,

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<v Speaker 1>is roughly a thousand times more expensive than the silicon

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<v Speaker 1>wafer because of gallium's rarity. Even though gallium is that

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<v Speaker 1>much more expensive than silicon, it's become a popular semiconductor

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<v Speaker 1>material in the latest generations of smartphones. Smartphones communicate with

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<v Speaker 1>cellular data networks using radio frequency chips or r F chips,

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<v Speaker 1>and r F chips made with gallium arsenide give off

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<v Speaker 1>less heat than silicon and can operate at higher frequency bands,

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<v Speaker 1>a requirement for five G networks. A little more than

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<v Speaker 1>of all the gallium consumed in the United States is

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<v Speaker 1>used to make r F chips and other types of

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<v Speaker 1>integrated circuits. However, one of the coolest applications of gallium

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<v Speaker 1>is in light emitting diodes, or l eds, which are

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<v Speaker 1>now used in everything from computer displays to traffic lights

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<v Speaker 1>to car headlights. L e d s are so popular

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<v Speaker 1>because they're super efficient they don't heat up. The first

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<v Speaker 1>visible light l eds were invented in the early nineteen

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<v Speaker 1>sixties when researchers at General Electric discovered the unique properties

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<v Speaker 1>of diodes made with various gallium alloys, that is, combinations

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<v Speaker 1>of gallium with arsenic, nitrogen, phosphorus, and other elements. In

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<v Speaker 1>a diode, electrons move through two layers of semiconductor material,

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<v Speaker 1>one with a positive charge and the other with a

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<v Speaker 1>negative charge. As free electrons from the negative side fill

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<v Speaker 1>holes in the positive side, they emit a photon of

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<v Speaker 1>light as a byproduct. Scientists have discovered that different gallium

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<v Speaker 1>alloys emit photons of different visible light frequencies. So gallium

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<v Speaker 1>arsenide and gallium phosphide produced red, orange, and yellow light,

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<v Speaker 1>while gallium nitride produces blue light. And not only do

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<v Speaker 1>l e d s produced light when connected to electricity,

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<v Speaker 1>but the process can be reversed. The special diodes inside

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<v Speaker 1>of solar cells are also made of galleum based semiconductors.

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<v Speaker 1>They take incoming light and separate it into free electrons

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<v Speaker 1>and holes, a generating voltage that can be saved in

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<v Speaker 1>a battery as electricity. The aerospace industry has been hot

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<v Speaker 1>on gallium for decades. All of the high end solar

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<v Speaker 1>panels that power satellites and long range spacecraft are made

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<v Speaker 1>with gallium arsenide, including the critical solar panels on the

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<v Speaker 1>Mars Exploration Rovers. At peak performance, the galleum based solar

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<v Speaker 1>cells on the Mars Rovers could produce nine hundred watt

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<v Speaker 1>hours of energy per martian day. But wait, there's more.

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<v Speaker 1>A Mendiola said. Medicine is beginning to use gallium too,

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<v Speaker 1>for detecting and treating certain types of cancers. Gallium sixty

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<v Speaker 1>seven is attracted to cells that replicate faster than normal,

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<v Speaker 1>which is what happens in a tumor. Gallium sixty seven

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<v Speaker 1>as a radioactive isotope of gallium that emits non toxic

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<v Speaker 1>gamma rays. A Radiologists can scan a patient's whole body

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<v Speaker 1>for tumors or inflammation from an infection by injecting gallium

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<v Speaker 1>sixty seven into their bloodstream. Because gallium sixty seven binds

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<v Speaker 1>to clumps, of fast growing cells. Those potential trouble spots

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<v Speaker 1>will then show up on a scan that's sensitive to

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<v Speaker 1>gamma rays. Gallium nitrate has also shown effectiveness in shrinking

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<v Speaker 1>and killing certain types of tumors, not just detecting them.

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<v Speaker 1>Today's episode is based on the article gallium boiled four

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<v Speaker 1>thousand and forty four degrees fahrenheit but will also melt

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<v Speaker 1>in your hand on how staff works dot Com. Written

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<v Speaker 1>by Dave Ruse. Brain Stuff is productive i Heart Radio

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<v Speaker 1>in partnership with how stuff works dot Com and it's

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<v Speaker 1>produced by Tyler Clang. Four more podcasts from my heart Radio.

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<v Speaker 1>Visit the iHeart Radio app, Apple Podcasts, or wherever you

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