MIT Chemistry Behind the Magic: Elements on Fire - TIB AV-Portal

MIT Chemistry Behind the Magic: Elements on Fire

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MIT OpenCourseWare

Dolhuh, John Harrop, Jessica

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MIT Chemistry Behind the Magic: Elements on Fire

Title of Series

MIT Chemistry Behind the Magic

Number of Parts

13

Author

Harrop, Jessica

Contributors

Essigmann, John

License

CC Attribution - NonCommercial - ShareAlike 4.0 International:
You are free to use, adapt and copy, distribute and transmit the work or content in adapted or unchanged form for any legal and non-commercial purpose as long as the work is attributed to the author in the manner specified by the author or licensor and the work or content is shared also in adapted form only under the conditions of this

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10.5446/42562 (DOI)

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MIT OpenCourseWare

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Abstract

The experiments described in these materials are potentially hazardous and require a high level of safety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT and Dow shall have no responsibility, liability, or risk for the content or implementation of any of the material presented.

Speech

Text

Image

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FireColourantChemistryChemical element

00:22

Chemical experiment

00:51

Chemical experiment

01:06

ColourantEmission spectrumChemical experiment

01:17

StrontiumBoronSodiumLithiumColourantMethanolBlue cheeseChemical experiment

01:41

PotassiumComputer animation

01:50

Chemical experiment

01:58

SaltChemical elementComputer animation

02:03

GraukäseBlue cheeseSodiumBoronColourantStrontiumFlameLithiumAtomChemical elementPotassiumAtomic numberMethanolEmission spectrumSalt

04:23

Chemical elementLeadExciter (effect)Computer animation

04:30

Hope, ArkansasComputer animation

04:36

Computer animation

Transcript: English(auto-generated)

00:02

Hi, I'm Jessica, and today I'm going to be talking about a chemical demonstration I like to call Elements on Fire. Let's watch as MIT's Dr. John Dolan, here he is, creates a rainbow of colors at the Cambridge Science

00:21

Festival. So what I'd like to do is do a grand finale by actually burning some elements, since we're talking about elements.

00:46

And we're going to have a little rondu music to go with this. So Clifton can go ahead and do that.

01:03

I've got some lithium, some boron, strontium, sodium, and potassium. So there should be quite a broad spectrum of colors here.

01:23

So the boron is a nice green color. The lithium is a beautiful red. The sodium back here is a yellow. We've got a little bit of strontium, which is kind of the bluish red.

01:41

I think the blue is probably the methanol. And the potassium is a little bit of a violet in with a yellow color. Can you see those?

02:03

So Dr. Dolan puts salts of five different elements in watch glasses. Lithium, boron, strontium, sodium, and potassium. He also adds a little methanol to each watch glass.

02:20

Then he lights them all on fire, and they produce flames of different colors. Lithium is red. Boron is green. Strontium is a blue red. Sodium is yellow. And potassium is violet with yellow streaks. So what's happening? Well, the flame heats up the elements, giving them more thermal energy.

02:42

This excites the electrons from their ground or lower energy state to an excited or higher energy state. This is what that looks like.

03:02

Since energy cannot be created or destroyed, any energy that was absorbed by the atom must be emitted again as the electron returns to the ground state. This energy is emitted as light. So why do different elements have different colored flames?

03:22

Because the difference in energy between the ground state and the excited state is unique for each element. And what does energy have to do with it? Well, the human eye perceives photons or light particles of different energies as different colors. So red light is a lower energy than yellow, which is a lower energy than blue.

03:41

Think about it like a rainbow spectrum. So energy increases along the spectrum. Red is low energy light, and violet is high energy light. Going back to our atoms' energy levels,

04:02

if the difference between the ground state and the excited state is smaller, the light particle is of lower energy. And we see that as a redder light. Conversely, if the energy gap is larger, the light particle is of higher energy, and we see that as bluer light.

04:21

And this is a simplified picture of what's happening. Each element has a unique set of excited states, which each leads to a different pattern of light, which we see as red, green, yellow, et cetera. Hope you enjoyed the video, and I'll see you next time.