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.
Stars are like headlights in a fog bank that’s impossibly thick in some places, and so thin as to be transparent in others. Sometimes, we get lucky enough for starlight to light up the fog. Other times, stars shine straight through it.
That “fog” is the interstellar medium. I’ve covered it in several posts already. We’ve gone over nebulae, the visible evidence of the stuff between the stars. I’ve talked about ways to study the interstellar medium. And I’ve introduced you to cool clouds, the clouds of mostly neutral hydrogen gas.
Now I want to introduce you to the intercloud medium. It’s different from cool HI clouds in that it’s ionized, rather than neutral.
Take a wild guess: how much energy do you think the sun generates?
Think about it. It definitely generates enough energy to power a world.
Humans depend on the photosynthesis of plants, which converts sunlight into energy. And that’s not all. Without energy from the sun, our atmosphere would behave very differently, and so would our oceans.
Everything that moves on Planet Earth does so because it has energy. And a lot of that energy comes from the sun. It doesn’t even stop there—obviously, the sun has plenty of energy to spare, if the recent influx of solar power means anything.
The sun is incredibly powerful. And it’s powerful enough to keep generating that kind of massive energy supply for billions of years.
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.
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.
“The Building Blocks of the Universe.” When you put it that way, atoms sound less like a topic specifically for a chemistry class and more like something astronomers might discuss.
They really are. I’ve got a fantastic reason to include atoms under astronomy, and its name is stellar spectra.
We’ve encountered stellar spectra before in these astronomy posts. When I wrote about the spectrograph, an instrument astronomers use to study data, I talked about spectral lines. I also promised we’d come back to elaborate on that later.
We’re not actually going to talk about the spectrograph in this post. I’m saving that for another time. For now, I’m going to cover atoms in a little more detail.