Basics of chemical reactions

Chemical reactions are reactions that are usually characterized by a chemical change, and they yield one or more products. Some of the clues that a chemical reaction has occurred are color change, solid forms, bubbles form, and heat or a flame is produced. The substance or substances,  initially involved in a chemical reaction are called the reactants. What the chemical reaction yields is called a product.

Here are some examples of chemical reactions

https://en.wikipedia.org/wiki/Combustion

http://www.grandinetti.org/chemical-reactions