Fully answer these questions in your laboratory notebook before coming to lab. f

Question

Fully answer these questions in your laboratory notebook before coming to lab. for numerical calculations. Using your textbook as a reference, explain why different cations would glow with characteristic colors when placed in a flame. Make a detailed flow chart showing how the cations in part II are separated and identified in your notebook. Write a net ionic equation for each reaction that occurs in the experiment. Consult a reference such as the "CRC Handbook of Chemistry and Physics" and record the solubility of lead(II) chloride in both hot water and cold water. Based on this data, why is the use of hot water critical to the success of this experiment?

Explanation / Answer

1) An atom has several shells of electrons, and each shell has a different energy. Heating an atom excites its electrons and they jump to higher energy levels, but they don't stay there very long. When the electrons return to lower energy levels, they emit energy in the form of light of a characteristic wavelength which is the color of the flame. Every element has a different number of electrons and a different set of energy levels. Thus, each element emits its own set of colors. For e.g. sodium has electron energy levels that give off yellow photons, cadmium has electron energy levels that give off brick red photons, and copper has electron energy levels that emit bluish-green photon.

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