Maria was right in her sratement... as the fireworks looks very bright and awsome because of chemical reaction ...which foes kn when they started igniting up.... As potassium ..magnesium nd many others chemicala are used to look the firework attractive.Hence , it is the because of CHEMICAL REACTION ...that resulta in Attractive Firework.
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Yes fireworks is the result of chemical reaction. firework is resalt of differant oxidation, reduction, and combution reaction. 
 when fireworks was made all chemical in soild form combine and put into cardboard compartments. the chemical which are presant are oxidizing agent, reducing agent, coloring agent (metal salt), and binders.
colors in fireworks are produced by metal salts like calcium salts, sodium salts, CuCl, sodium nitrate etc.
when firework is ignited chemical which presant in it are react with each other and produce lightning & sound. in roket power needed to lift into the air is provided by the highly exothermic combustion reaction.