How+do+they+get+the+different+colors?

Pretty Colors! So when you're sitting in the park on the Fourth of July, you don't just see white fireworks, right? They can make almost any color in the rainbow, it seems! So... how do they do it? To find the answer, we have to look to the periodic table...

Ta-da! Well, it's a little more complicated than that. You see, when elements are heated up and then rapidly cooled down, the extra energy given off from the cooling process is given off as light. The thing is, each element has its own amount of energy that it loses through the cooling process. The result is different colored lights. Let's take a deeper look at how the elements make different colors...

Light, colors, and energy Let's look at calcium for a minute to see how this works. When calcium is heated, the atoms absorb energy. The electrons of the atom use the energy to move up the ladder, so to speak, to a higher energy state. That level of energy does not last long, though, and the atoms quickly lose the energy they gained in the form of light. This is true for any element. The difference is in the amount of energy each element releases. Calcium releases between about 190 and 195 kilojoules (kJ) of energy, while copper releases between 245 and 265 kJ of energy. So how does this affect the color each element gives off? Well, even though they are all losing energy through light, this light will have different energy levels depending on how much energy is released. The more energy that's released, the more goes into the light, the shorter the wavelengths of the light. As the energy changes, so does the wavelength, which creates different colors. This picture shows the relationship between energy, wavelength, and color. Red has the lowest wavelength and the lowest energy while violet had the highest wavelength and energy level. Each element gives off a different amount of energy, a different wavelength, a different color. So by adding different elements to the fireworks "recipe," pyrotechnicians (the people who make the fireworks) can create different color explosions. Here is a table to show which elements make which colors: ** || ** strontium salts, lithium salts lithium carbonate, Li2CO3 = red strontium carbonate, SrCO3 = bright red ** || ** 652 ** || || ** orange ** || ** calcium salts calcium chloride, CaCl2 ** || ** 668 ** || || ** yellow ** || ** sodium salts sodium chloride, NaCl ** || ** 610-621 ** || || ** green ** || ** barium compounds + chlorine producer barium chloride, BaCl2 ** || ** 589 ** || || ** blue ** || ** copper compounds + chlorine producer copper(I) chloride, CuCl ** || ** 505-535 ** || || ** purple ** || ** mixture of strontium (red) and copper (blue) compounds ** || ** 420-460 ** ||
 * || **Color** || **Compound** || ** Wavelength (nm)** ||
 * [[image:http://scifun.chem.wisc.edu/chemweek/fireworks/images/red.GIF width="40" height="40"]] || ** red
 * [[image:http://scifun.chem.wisc.edu/chemweek/fireworks/images/orange.GIF width="40" height="40"]]
 * [[image:http://scifun.chem.wisc.edu/chemweek/fireworks/images/yellow.GIF width="40" height="40"]]
 * [[image:http://scifun.chem.wisc.edu/chemweek/fireworks/images/green.GIF width="40" height="40"]]
 * [[image:http://scifun.chem.wisc.edu/chemweek/fireworks/images/blue.GIF width="40" height="40"]]
 * [[image:http://scifun.chem.wisc.edu/chemweek/fireworks/images/purple.GIF width="40" height="40"]]
 * [[image:http://scifun.chem.wisc.edu/chemweek/fireworks/images/silver.GIF width="40" height="40"]] || **silver** || **burning aluminum, titanium, or magnesium** ||  ||

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