How can we make different colored flames?
How are these different color flames possible? We can use elements’ atomic emission spectra to produce these colorful results. The first is Lithium, the second is Arsenic, the third is Copper; all are held over a Bunsen burner. Each element has a unique electron configuration. When these electrons are excited (and gain energy), they move into higher electron orbitals. When they come back down to their original state, they emit a color, depending on the difference in energy between the two orbitals. As each element has unique electron configurations, they also have unique emission spectra-- that is they produce different colors of light. We can use their unique emission spectra in a variety of ways.
- One way to see emission spectra is to hold the element under flame. Different elements glow differently. What color does potassium produce? Copper? Which elements produce your favorite colors?
- Emission spectra can also help us when we can’t directly sample a material to check its chemical composition. How is emission spectra used in astronomy?
- Go to http://chemistry.bd.psu.edu/jircitano/periodic4.html and look at the various emission spectra of elements. Why do larger molecules’ emission spectra tend to be more complex?