What is uranium?

Welcome to Science is Not Boring by kidopoly.com. I'm Mira. And I'm Finn. Before we begin, we have some absolutely huge shout-outs today. A big hello to Eva in Denver, who is turning seven and specifically asked for an episode all about uranium and radiation. Great pick, Eva. This is going to be a wild one.

We also want to say a massive, super exciting hello to William, Laney, and their brand new baby sister, Kendall. Welcome to the world, Kendall.

And finally, we want to wish a very happy 7th birthday to Ramona in Texas. We hope your birthday is as amazing and energetic as today's topic.

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Today, we're talking about something invisible, powerful, and absolutely mind-blowing. Wait, how mind-blowing are we talking? Well, imagine holding a tiny little cylinder of metal, about the size of the tip of your pinky finger. It weighs just 10 grams. Okay, that sounds pretty small and harmless. That tiny piece of metal contains as much energy as one entire tonne of coal.

One ton? From something the size of my fingertip? Exactly. Today we're diving inside the heaviest natural atom on Earth to find out what uranium is and why radiation is so ridiculously powerful.

Okay, so what exactly is uranium? Is it a glowing green rock?

Actually, in its pure form, uranium is just a shiny silvery grey metal. But what makes it special is what's happening deep inside it at a microscopic level. You mean inside its atoms? Yes. Everything in the universe is made of atoms. And atoms have a centre called a nucleus, which is made of tiny particles called protons and neutrons.

Right, like hydrogen is super light because it only has one proton.

Exactly. But uranium is the heaviest element that naturally exists in large amounts on Earth. A typical uranium atom has 92 protons and a massive 146 neutrons.

Whoa, 92 protons and 146 neutrons? That's 238 particles crammed into one tiny centre.

It is incredibly crowded. Because it has so many particles, uranium is ridiculously dense. Think about a regular gallon jug of milk in your fridge. It weighs about 8 pounds, right? Heavy, but I can carry that no problem. But if you poured out the milk and filled that exact same jug with liquid uranium, it would weigh a staggering 150 pounds.

That's as heavy as a grown adult squished into one single milk jug.

Ugh, I definitely could not carry that. I would drop it immediately. Where do we even find this incredibly heavy stuff? Does it just sit around on the ground waiting to be tripped over?

It's actually all around us in the Earth's crust. There are tiny amounts in the rocks in your backyard, in the dirt, and even dissolved in the ocean water. Wait, I've been swimming in uranium at the beach. Just tiny, tiny trace amounts. It's completely harmless when it's that spread out. But to get enough to actually use, miners have to dig deep underground to find special rocks called uranium ore.

And that brings us to Germany. Way back in the year 1789. What happened in 1789? A German chemist named Martin Heinrich Klapproth was experimenting with a heavy pitch black rock called pitchblend.

Pitchblend? That sounds like something a wizard would use in a magic potion.

It was a very mysterious mineral. Silver miners used to find it deep in the mountains and just throw it away because it ruined their other metals. They called it Bad Luck Rock. So what did Klaproth do with the Bad Luck Rock? He was a genius at taking minerals apart. He crushed this heavy black rock in his lab, mixed it with strong chemicals and acids, and extracted a strange yellow powder.

Did he know what it was right away?

He realised he had discovered a brand new, extremely heavy element. He named it uranium, after the newly discovered planet Uranus. He thought it was just a neat, colourful metal that glassmakers could use.

Okay, so he found a heavy metal. But when does the crazy energy part happen? Like the ton of coal thing?

That took another 150 years to figure out. You see, remember how we said uranium's nucleus is packed with 238 particles?

Yeah, it sounded way too crowded.

It is. It's so bulky that it can't hold itself together forever. Over millions of years, the uranium nucleus slowly breaks down. It naturally throws off tiny pieces of itself, like invisible rays of energy in particles. Wait, it's just sitting there shooting out invisible rays. Yes, and that amazing process is called radioactivity.

Scientists in the late 1800s finally discovered these invisible rays were incredibly energetic.

But if it's doing it really slowly over millions of years, how do we get that massive blast of energy you talked about earlier?

That brings us to 1938, and a mind-blowing discovery by a brilliant scientist named Lisa Meitner and her nephew Otto Frisch.

What did they do? Did they crush the rock again?

No, other scientists have been firing extra tiny neutron particles at uranium atoms in a lab just to see what would happen. They thought the uranium would just swallow the neutron and get slightly bigger.

Like adding one more person to an already stuffed elevator.

Exactly. But instead, the results from the lab made absolutely no sense. Lisa Meitner and Otto Frisch were taking a walk in a snowy Swedish forest on Christmas Eve when they finally figured it out. Figured what out? They sat down on a fallen tree trunk, doing complicated physics math on scraps of paper right there in the snow.

They realized that when the extra neutron hit the crowded uranium nucleus, it didn't stick. Then what did it do? The whole atom stretched out, jiggled like a water balloon in slow motion, and completely split in two separate halves.

They split the atom! I thought atoms were the smallest, most unbreakable things in the universe.

Everyone did. The idea that an atom could break was considered totally impossible. Yes, they split it, and they named this incredible reaction nuclear fission.

That is so cool. But wait, where does the energy come from?

Here's the absolute craziest part of their discovery. When you measure the two new halves, they actually weigh slightly less than the original atom. A tiny bit of the atom's matter just vanishes completely into thin air. Where did it go? It turned directly into pure energy. And when an atom splits, it also releases extra neutrons that fly out at incredible speeds and hit other uranium atoms, splitting them too.

Like a microscopic game of bowling.

Exactly. It creates a chain reaction. Splitting just one atom releases millions of times more energy than chemical burning, like burning coal or wood.

So that's how that tiny pinky-sized pellet of uranium equals a whole ton of coal. The energy was trapped inside the atom the whole time.

That discovery entirely changed human history. Today, we use safely controlled nuclear fission inside massive buildings called nuclear power plants. What do they do inside the plants? The splitting atoms create immense heat. That heat boils water into super hot steam. And the steam spins giant fans called turbines to create electricity for millions of homes and entire cities.

And since nothing is actually burning, it doesn't make dark smoke like a coal fire, right? Exactly.

It generates massive, continuous amounts of clean electricity without pumping carbon dioxide pollution into the air we breathe. A single plant can power a whole city day and night.

That is incredibly useful. What else can it do? You mentioned hospitals earlier.

Yes. The science of radiation is used by doctors every single day. Doctors use radioactive isotopes to perfectly sterilise important medical equipment so it's safe for patients. And to take highly detailed scans of the inside of our bodies to figure out exactly what is making someone sick.

Okay, so it gives us clean power for our houses and helps doctors save lives. That's pretty cool.

It even goes to the farthest reaches of space. Scientists use a close relative of uranium, called plutonium, which we actually make from uranium, to build special batteries. They use the heat from the radioactive decay to power deep space probes, like the Voyager spacecraft.

Wait, isn't Voyager the one that has been flying for over 45 years?

Yes. It is currently billions of miles away from Earth, and it's still sending messages back, all powered by that amazing atomic energy.

That is incredible. Are there any other weird things uranium was used for?

Are you ready for a wild fun fact? Before people knew about the massive energy hiding inside uranium, glassmakers used to mix tiny amounts of it into glass to make cups and bowls. Wait, they drank out of uranium cups? Yep, they called it Vaseline glass because it had a slight yellow colour. And the coolest part?

If you shine an ultraviolet black light on it, the uranium glass glows a brilliant, bright neon green.

Haha, okay, a glowing green cup is basically the coolest thing ever. Alright, Finn, time for the quiz. Are you ready? Okay, my brain is packed like a uranium nucleus. But I'm ready! First question.

How many protons does a typical uranium atom have? Next one. Which German chemist discovered uranium in the year 1789? Question three. What is the scientific name for the process of splitting an atom? Here's number four. A uranium fuel pellet is the size of a fingertip but has the energy of how much coal.

Last question. What happens to old uranium glass when you shine an ultraviolet light on it? Great job! Let's see how you did. The first answer is a typical uranium atom has 92 protons. For question two, the chemist who discovered it was Martin Heinrich Klaproth. three, the answer is splitting an atom is called nuclear fission.

Question four. That tiny uranium pellet equals the energy of one whole tonne of coal. And the final answer is under UV light, uranium glass glows neon green.

Wow! From heavy black rocks found by miners in 1789 to scientists splitting atoms in the snow and now powering deep space probes billions of miles away. My mind is officially blown.

Science is just amazing like that. To think all that world-changing energy was hiding inside a tiny invisible atom, just waiting for human curiosity to figure it out.

Speaking of amazing, if you loved learning about Lise Meitner splitting atoms in the snowy woods, we'd love it if you could leave us a five-star review.

Yes, just scroll down on your podcast app and tap the five stars. It helps other curious kids find the show. Oh, and we have sister shows too. History and philosophy is not boring, and maths is not boring. Go give those a listen and a follow as well.

And if you want a shout out on the show, or just want to tell us what your favorite fact was, email us at hello at kidopoly.com.

See you next time on Science Is Not Boring. Bye everyone.

What is uranium?

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