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Spectroscopy ~ Photons and Flame Tests



When energy is added to an atom in the form of light, heat, or electricity, the electrons absorb this energy and, as a result, move to higher energy levels called excited states. However, because it is more stable for electrons to have lower potential energies whenever possible, they eventually return to their original orbitals.



When electrons fall back toward the nucleus, energy is released from the atom as light. Depending on the distance the electron falls, and the amount of energy given off, a specific color of light is emitted. We can use the color of the light emitted by an element to determine the different locations of its electron orbitals. The differences in orbital location and potential energy values are unique for every element. This means that each element gives off a unique color, based on the combination of the wavelengths of light it produces.


It is common in science to take an unknown element or compound, discovered in nature or created in a reaction, and compare its properties to different known substances to see if it can be identified. The flame test is one way that scientists can identify the elements present in a given sample.



A common lab in Astronomy is called “flame tests” and we will simulate that here.


First, observe each element (shown in the flame of the Bunsen burner). Note the flame color.  



Second, view the two unknown elements and identify them by comparing their flame color to the known elements you observed.



Flame color

Identity of element based on flame test

Unknown 1

click for flame test

Unknown 2

click for flame test



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