How Were Atoms Discovered?

Welcome to my fourth “Science Answers” post! If you have a question, you can ask it in the comments here, or ask it in an email. Or find me on Facebook!

Q: (1) How did scientists find elements in the first place? Could there be more undiscovered elements?
(2) How did scientists create the periodic table?
(3) How do we know that everything is made up of atoms, when atoms are so small that they can’t even reflect light (a necessity for seeing them)?
(asked by Mukesh Garbyal)

Really good questions! I was asked these in a comment on my post “Types of Atoms,” and chose to answer them in a post of their own.

Let’s take this apart. I actually want to address the third part of the question first, since it contains a misconception: atoms can reflect light. Their interaction with light is actually why we can see anything in the world.

How?

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Star Stuff & Cecilia Payne

quote-do-not-undertake-a-scientific-career-in-quest-of-fame-or-money-there-are-easier-and-cecilia-payne-gaposchkin-91-25-91.jpg

If this quote really is from Cecilia Payne, then she had the right idea—at least for a female astronomer in the 1920s. Women in science back then faced an uphill battle to get recognized for any discoveries they made, and Payne was no different.

What’s so special about Payne, you might ask? Well, she wasn’t just one of the many “unsung heroes” of modern science. She was the one who figured out what stars are made of.

Yeah, that’s right. She sent a probe to the sun, collected a jar of star stuff, and brought it back to her laboratory…

Um, no, not really. It wasn’t that easy.

In fact, it was very difficult. She had far too many roadblocks than were fair. But she wasn’t out for money or recognition. She was just in it for the science. And science was what she got…

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The Balmer Thermometer

hot star.jpg

How hot would you say this star is? Take a wild guess.

Well…sorry, but I’m going to stop you for a moment just to make sure we’re all using Kelvins. The Kelvin scale is like the Celsius scale, except water freezes at 273 K instead of 0℃. 0 K is absolute zero, which is purely theoretical and doesn’t exist.

Now can you guess this star’s temperature?

I’ll give you another hint. This is a real photograph, so it’s impossible for this star to be any star other than our sun. How hot do you think our sun is?

Okay…I’ll tell you. It’s about 5800 K, which—for those of you unfamiliar with Kelvins—is about 5527℃. Kinda crazy, huh?

Next question. How do we know this? I mean, it’s not like we stuck a thermometer in the sun’s surface and actually measured it, right?

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How Atoms Work

atom photo.jpg

Have you ever seen something like this?

I’m going to venture a wild guess and say you haven’t, since scientists have only recently been able to take this kind of image. I learned about it in my biology class this semester, and the professor said that it was a landmark achievement.

You’re looking at an atom.

Yes, that’s right. You’re looking at a single, microscopic building block of matter.

Let me give you an idea of just how small this is. Millions of the smallest atom in the universe can fit lined across the diameter of a single pinhead.

But I’ll ask you another question. If I showed you an image like the one below, would you immediately think, “atom”?

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Types of Atoms

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Does this look familiar?

It might, or it might not. If it does, you might recognize it as the periodic table of the elements—more often known as simply the “periodic table.” It’s an ingenious way to organize elements that has worked for scientists for quite some time.

To fully appreciate the ingenuity of the periodic table, I’d have to take you through a few chemistry lessons. Never fear, I have every intention of doing so—later. For now, though, I just want to address enough of the world of atoms to talk about stellar spectra.

That just means the spectrums we get from stars, by the way. (Spectra is plural for spectrum.) And that means…well…we’ll talk about it later. Let’s talk about the different types of atoms first.

Atoms are the building blocks of the universe. Which means there must be different types. But what are they?

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