Happy 4th of July!

It's really appropriate that we use fireworks to celebrate the 4th of July, a day when we declared our independence from the Kingdom of Great Britain. Why? Because of the chemistry involved in fireworks.

Basically, without getting OVERLY nerdy (let's keep it to an "I'm interesting at cocktail parties" minimum, here, people), there's an oxidizer (stuff that acts as fuel and produces oxygen) and a reduction agent (something that eats up the oxygen). You might remember from chemistry that within an atom, there's a nucleus with some protons in it and the electrons in orbits around the nucleus. Well, a firework's color comes from those electrons becoming excited and unstable (due to the reaction between the oxidizer and reduction agent). When they're excited, then jump to a higher energy level and exhibit some sort of color. They're doing their own demonstration of the Declaration of Independence and the Revolutionary War that followed!

What color it is depends on what element or compound is used. Check out the chart below:

Color	Compound
Red	strontium salts, lithium salts lithium carbonate, Li2CO3 = carmine red strontium carbonate, SrCO3 = bright scarlet red
Orange	calcium salts calcium chloride, CaCl2 calcium sulfate, CaSO4·xH2O, where x = 0,2,3,5
Gold	incandescence of iron (with carbon), charcoal, or lampblack
Yellow	sodium compounds sodium nitrate, NaNO3 cryolite, Na3AlF6
Electric White	white-hot metal, such as magnesium or aluminum barium oxide, BaO
Green	barium compounds + chlorine producer barium chloride, BaCl+ = bright green
Blue	copper compounds + chlorine producer copper acetoarsenite (Paris Green), Cu3As2O3Cu(C2H3O2)2 = blue copper (I) chloride, CuCl = turquoise blue
Purple	mixture of strontium (red) and copper (blue) compounds
Silver	burning aluminum, titanium, or magnesium powder or flakes

I only beg to differ (on behalf of my chemistry teacher, Mrs. Bachman) in a few areas, but thank you about.com:
copper = green
cobalt =blue
potassium = purple

So when you're watching the fireworks tonight (weather permitting of course) and you want to seem like a big nerd, yell out the names of the appropriate elements as their corresponding fireworks colors light up the sky. Happy 4th!