2. If available a blue cobalt glass filter is used since sodium is often present in water (sodium gives a yellow flame test). Filters usually remove their complimentary color, and blue is compliment to yellow. So when white light (white light can be thought of as red, green and blue light) passes thru a blue filter, why does it appear blue?

3. When does the atom (the ion we hold in the flame) emit the light we observe? When the electron moves outwards or when it moves inwards? Explain. [Hint: emitting light is emitting (giving off) energy, absorbing light is absorbing energy.]

4. If an ion absorbs mostly the light wavelength that is blue, and most of the emitted light was yellow and red (other wavelengths), would we see more blue or less blue than if the ion was not present? Explain.