Understanding Flame Tests and Emission Spectra

1. Understanding Flame Tests and Emission Spectra

2. Electron Cloud Arrangement The electron cloud is arranged into various regions called energy levels. The energy level closest to the nucleus is the lowest energy level and numbered “1”. Each energy level after increases in number and requires more energy to be occupied.

3. Electron movement Electrons moving in the electron cloud require a certain amount of energy. This energy allows them to move around the nucleus. Remember that there aren’t really fixed orbits, but the image helps give you an idea of what we’re talking about.

4. Electron Excitation When electrons have their “usual” amount of energy this is called the ground state. These electrons travel around the lowest possible energy level. However, if an outside source (like electricity or fire) provides energy to these electrons they will gain energy and “jump” to a higher energy level. This is known as the excited state.

5. Fall back After a short amount of time, the electron will lose this extra energy, and return to the original lower energy level. In the process the extra energy is released as a photon (light)

6. Photons = light The amount of energy released by the excited electron can be interpreted by our eyes as various colors.

7. Light Visible light is only a small portion of the electromagnetic spectrum. Our eyes can only interpret a small range of these waves. Imagine what X rays would look like? Or Microwaves?

8. Color and Energy Each color we can see, is actually a different wavelength of energy. Reds have very large wavelengths, and carry less energy than Blues and Purples, which have shorter wavelengths and pack more energy.

9. Spectroscopy and the elements • The experiment conducted takes advantage of prisms, and their ability to break light up into the individual colors (wavelengths) that are present.

10. Each element produces a unique patterns of light, due to the photons released by the excited atoms falling back to their ground state. Therefore, the banding patterns can be used to ID elements.

11. Flame Test Similar to the emission spectrum, elements, when burned also give off light. Elements give off signature colors, and can be used to help ID elements

12. Objective Identify the unknown element using the spectroscopes. It is one of the other 5 you are observing! Identify the unknown elements using the flame test.