Using a Spectrometer to find out what something is made of

 

Let's say you are sending a spacecraft to Mars. You'd like your spacecraft to help you figure out what the rocks on Mars are made of.

Or, let's say you'd like to know what gases are in the planet Jupiter's atmosphere.

Or, maybe a strange gas has entered your school building and you'd like to figure out if it's dangerous or not.

A spectrometer will help you in all these cases.

It turns out that different substances absorb or emit light at different wavelengths in the ElectroMagnetic Spectrum.

If you shine the light you get from burning sodium into a prism or diffraction grating or other spectrometer, you'll find that the light comes out in bands of color at different places on the spectrum.

The amazing thing is, every time you see burning sodium, you'll see this same pattern of light if you send it through a spectrometer. You will always see those same bright aqua and green lines by themselves in the middle of the spectrum. These lines are called spectral lines, and they are related to the way the atoms in the material are arranged.

Scientists have made catalogs of the spectral lines from thousands of different materials. So, if you have an unknown substance, you can match up the spectral lines it produces with the substances in these catalogs to figure out what your substance is made of. Pretty clever, right?

We're going to make our own simple spectrometer, and then we'll practice finding the spectral lines of substances. Finally, we'll try to figure out what some unknown substances are made of using the Whyville Spectrometer.