Who was Dmitri Mendeleev?

0:46 Welcome to Science Is Not Boring by Kidopoly.com. I'm Mira. And I'm Finn. We have some massive shout-outs today. First, a big hello to Lucas, who is 10 in Alberta, Canada. He has listened to all our shows and asked to learn more about Dmitry Mendeleev. This one is for you, Lucas. And a big hello to Leon, too.

1:10 We also want to say a very happy birthday to Joseph, who is turning 8 today.

1:16 And a very happy birthday to his sister Lydia, who also shares an October 3rd birthday. They are listening with their sister Eden right now. We hope you both have wonderful celebrations.

1:27 If you haven't already, tap follow wherever you're listening so you never miss an episode.

1:33 Okay, Mira, my brain is ready. What incredible scientific mystery are we diving into today?

1:39 Today, we are exploring the ultimate recipe book for the entire universe. I want you to close your eyes and imagine you had a giant box of Lego, but instead of plastic bricks, it was filled with just 118 special, invisible building blocks.

1:56 Wait, only 118? But the universe is gigantic! There are billions of galaxies, trillions of planets, and millions of weird bugs on Earth alone. How can absolutely everything be made from just 118 blocks? It sounds impossible, but it is completely true.

2:15 Those special building blocks are called chemical elements. Every single thing you can touch, see, smell, or breathe is made of them.

2:26 So what exactly is an element? Like, can you actually hold one in your hand?

2:31 Absolutely! An element is a pure substance that cannot be broken down into anything simpler. Think of a heavy, solid bar of pure gold. If you chop that gold bar in half, and then in half again, and keep chopping it with a microscopic laser until you reach the very last tiny speck.

2:53 Let me guess. It is still just gold?

2:56 Exactly! Down to a single invisible atom, it is still gold. Oxygen is an element. Iron in your blood is an element. Silver, carbon and titanium are all elements.

3:11 Okay, so if everything is just a mix of these elements, who finally figured out how they all fit together? Was it a massive team of superscientists with high-tech computers?

3:23 Actually, the biggest breakthrough came from one single man trying to solve a massive headache. By the year 1869, scientists had discovered exactly 63 different elements. But the information was a complete and total mess.

3:40 A mess? Like throwing a 1,000-piece puzzle on the floor and throwing away the box. Exactly like that.

3:48 Scientists knew these 63 elements existed, and they knew the exact atomic weight of each one, which is basically how heavy its atoms are. But they had absolutely no idea how the elements related to each other.

4:02 So they just had a giant, confusing list of random rocks, metals, and gases.

4:08 Yes, and that is where our star scientist steps in. His name was Dmitry Mendeleev. He was a brilliant Russian chemist, living in the city of St. Petersburg.

4:20 What was it like there? I'm picturing lots of freezing snow.

4:24 Oh, it was a brutal winter in February 1869. Outside his window, the city was covered in deep snow, with freezing winds howling off the frozen Neva River. But inside his warm, incredibly messy study, Dimitri was working frantically. Dimitri was trying to write a chemistry textbook for his university students, and he desperately wanted to organise these 63 chaotic elements into something that actually made sense.

4:54 How do you even begin to organize all the building blocks of nature? Did he sort them by colour? Or maybe how heavy they were?

5:02 He tried sorting them by weight, but that wasn't enough. Dimitri noticed that certain elements acted in very similar and sometimes dangerous ways. For example, there was a group of super soft metals, like sodium and potassium, that would literally catch fire or violently explode the second they touched water.

5:25 Exploding water! That is terrifying, but also kind of amazing.

5:31 And then there were elements like chlorine and fluorine that loved to combine with metals to make different kinds of salts. Dimitri wanted to find the hidden mathematical pattern tying all these crazy behaviours together. So he borrowed an idea from one of his favourite hobbies.

5:51 Please tell me he played extreme sports with the explosive metals.

5:55 Not quite. He loved playing a card game called Solitaire, which is also known as Patience. So, he took a stack of exactly 63 blank cardboard cards.

6:07 Let me guess. He made one card for every single known element.

6:12 Spot on! He created the ultimate scientific trading cards. On each card, he carefully wrote the element's name, its atomic weight, and its special chemical superpowers, like how it reacted to heat or oxygen.

6:28 That is actually genius. It's like building your own custom deck of trading cards, but for actual universe science.

6:35 Exactly! Then he started pinning them to the wall of his laboratory. He arranged them in a long line based on how heavy their atoms were, from the absolute lightest, which is hydrogen, all the way up to the heaviest ones.

6:51 Did it work right away? Did he solve the giant puzzle?

6:55 No, it was incredibly frustrating. The pattern kept breaking. He stayed awake for three entire days and nights, shuffling the cards, moving them around the wall, desperately trying to make the puzzle fit.

7:10 Three whole days without sleeping. I get super cranky if I stay up even one hour past my bedtime.

7:17 He was completely exhausted. Finally, he could not keep his eyes open anymore. He slumped down at his heavy wooden desk and fell fast asleep. And that is exactly when something downright magical happened.

7:33 What? Did a huge gust of wind blow all his 63 cards out the window?

7:39 No! Dimitri later wrote that while he was fast asleep, he had an incredibly vivid dream. In his dream, he saw a giant grid, almost like a chessboard, and all the elements fell perfectly into their exact right places.

7:55 Wait, you're telling me he literally dreamt the mathematical answer to the universe while taking a nap?

8:03 Yes! He woke up with a start and immediately grabbed a piece of paper to sketch what his sleeping brain had figured out. When he lined them up in rows by their weight and then started new rows at just the right spots, the elements that behaved exactly the same way lined up perfectly in vertical columns.

8:23 That is the most satisfying thing I've ever heard. The puzzle was finally solved.

8:29 Well, here is the absolute wildest, most daring part of the story. When he lined up the cards, the grid wasn't a solid block. There were gaps. Blank, empty spaces where the mathematical pattern said an element should be, but he didn't have a card for it.

8:49 Uh-oh. Did that mean his dream table was actually broken?

8:54 That is what many other scientists thought. They mocked him. But Dimitri was so confident in his pattern, he did something incredibly brave. He left the spaces completely blank and told the entire scientific world, these are missing elements that we just haven't dug up yet.

9:13 Whoa! So he predicted things that literally no human being on Earth had ever laid eyes on.

9:21 Yes, he boldly predicted exactly how heavy they would be, what colour they would be, and the exact temperatures where they would melt. Let's fast forward just six years to 1875. A French scientist discovered a brand new shiny metal and named it gallium.

9:39 Did it fit perfectly into one of Dimitri's blank spaces?

9:43 It was an exact perfect match. Dimitri had predicted its atomic weight would be 68. Gallium's actual weight turned out to be 69.7, and he predicted it would melt at a freakishly low temperature.

9:59 Wait, how low? Like a hot summer day low?

10:03 Yes, gallium melts at exactly 85.58 degrees Fahrenheit. Since human body temperature is around 98 degrees, if you held a solid chunk of gallium, it would literally melt into a shiny silver puddle right in the palm of your hand.

10:21 That is completely mind-blowing. So when that French scientist found gallium melting in his hand, everyone realised Dmitry's crazy card game was right.

10:31 Exactly! Dmitry Mendeleev hadn't just organised a simple list, he had invented the periodic table of elements, which is one of the single most important tools in the entire history of science. It hangs in almost every single science classroom on Earth today.

10:48 So Lucas was totally right to ask for an episode about him. But wait, you said there are 118 elements now. Dimitri only had 63 cards.

10:59 That's right. Over the last century and a half, scientists have filled in every single blank space. But here is a wild fact. Only 94 of those 118 elements are actually found naturally on Earth.

11:13 Where did the other 24 come from? Did they crash here on meteorites from deep space?

11:19 Nope. Human scientists literally created them inside giant laboratories. They use massive machines called particle accelerators to smash atoms together at nearly the speed of light to make totally new elements.

11:33 We make our own elements by smashing them together. That sounds dangerously awesome. What is the weirdest element out there?

11:42 One of the most bizarre natural elements is called Francium. It is so incredibly rare and wildly unstable that scientists calculate there is only about 20 to 30 grams of it in the entire Earth's crust at any given second.

11:57 Wait, 20 grams? That weighs less than a single slice of bread. In the whole entire world.

12:04 Yep, Francium atoms literally pop into existence deep underground and then break apart almost instantly. If you somehow manage to gather a visible chunk of it, it would be so radioactive that it would instantly vaporise itself in a massive burst of intense heat.

12:22 Okay, I think I will definitely stick to nice, safe, boring elements like carbon and oxygen, thank you very much.

12:30 Good plan. But thanks to Dmitry Mendeleev, his deck of cards, and a very lucky nap, we know exactly where every single one of those extreme elements belongs in the universe. Alright Finn, time for the quiz! Are you ready?

12:45 Okay, I'm ready. Let's do this.

12:48 First question. How many elements were known to scientists in the year 1869? Next one. What was the full name of the brilliant Russian chemist who organized them? Question three. What card game did he use to organise the elements by writing them on blank cards? Here's number four. What specific element melts at 85.58 degrees Fahrenheit, turning to liquid right in your hand?

13:31 Last question. How many total elements are on the periodic table today? Great job! Let's see how you did. The first answer is there were exactly 63 elements known back then. For question two, his name was Dmitry Mendeleev. The answer to number three, he used the card game solitaire, which is also called Patience.

14:02 For question four, the amazing melting metal is called gallium. And the final answer is there are exactly 118 elements today.

14:13 Wow, so absolutely everything around us, from the deepest ocean trenches to the farthest exploding stars, is made from just those 118 building blocks. That is amazing.

14:26 It really is. Science is honestly like the best mystery novel ever written, because it is all completely real.

14:34 If you enjoyed learning about the ingredients of the universe with us, please leave us a five-star review.

14:40 Yes! Just scroll down on your app and tap the five stars. And maybe leave a review telling us which element on the periodic table is your favourite.

14:49 Make sure you tap follow on this app too. And oh, we have sister shows. Go give history and philosophy is not boring, and maths is not boring, a listen and a follow as well.

15:00 And if you want a shout out on the show, just like Lucas, Leon, Joseph, Lydia, and Eden, or if you just want to say hi, email us at hello at kidopoly.com.

15:12 See you next time on Science is not boring.