Flame Test Lab (Make-up) Name _______________________ Pre-lab questions: 1. Bohr's important discovery was that energy levels of electrons are quantized (only existing in certain, specific levels). In what year was this discovery made? 2. What happens to an electron when energy is added? 3. What is released when an electron loses energy? 4. What determines the frequency (color) of photons? Click on the links below and gather data about the elements: http://www.trschools.com/staff/G/CGirtain/Weblabs/spectrolab.htm http://webmineral.com/help/FlameTest.shtml Spectroscopy Lab Data Sheet Part 1 —Known elements flame tests Part 2 —Unknowns ELEMENT Barium Calcium Sodium Rubidium Potassium Lithium UNKNOWN 1 2 FLAME COLOR ELEMENT 1. How do these emission spectra compare in terms of colors and line positions? Are they identical? What is similar? What is different? 2. Fill in the chart below. Element with greatest number of clearly visible emission lines (Na, Ne, Hg, He) Longest wavelength in the Continuous spectrum (in nanometers) Color of light for the longest wavelength Element with the fewest number of clearly visible emission lines (Na, Ne, Hg, He) 1. ALL excited electrons give off energy when they return to their ground state from an excited state. Why don’t all heated substances give off colored light? 2. Sodium ions give off a yellow/orange colored flame when heated. Does this mean that all substances that give off a yellow/orange flame when heated contain sodium? Explain your answer. 3. Explain how knowledge of flame tests would be useful to a fireworks designer. 4. What particles are found in the chemicals that may be responsible for the production of colored light? 5. Why do different chemicals emit different colors of light? 6. Why do you think the chemicals have to be heated in the flame first before the colored light is emitted? 7. Colorful light emissions are applicable to everyday life. Where else have you observed colorful light emissions. Are these light emission applications related? Explain. 8. What is the characteristic flame color for Sodium, Lithium, Barium, Copper, Cesium, and Calcium? Explain why.