There are a lot of different kinds of chemical reactions, and no one way to group them that everyone agrees on. But these are some important kinds of reactions:
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To find out more about chemistry, check out these books from Amazon.com or from your library:
Atoms and Molecules (Usborne Understanding Science) , by Roxbee-Cox (1991). Ages 9-12. A basic introduction.
Chemistry (DK Eyewitness Books), by Ann Newmark and Laura Buller (2005). DK is a respected series.
Simple Chemistry, Grades 4-6, by Evan-Moor (2008). Ages 9-12. Good simple projects to illustrate concepts.