 Chemical reactions are reactions where there is a chemical change in the substances that are combined and new substances are formed.  There are chemical reactions taking place everywhere and everyday. Lighting a match, starting a car, walking, eating all involve chemical reactions

 Chemical reactions can be written as equations where the reactants react that result in or produce products.

 Two or more substances combine to produce a new product  General equation ◦ X + Y XY  Often the reactants in a syntesis reaction are elements ◦ Ex.

 In a decomposition reaction, a compound breaks down into two or more, simpler compounds or elements ◦ General equation – XY X + Y  We can think of decomposition reactions as the opposite of synthesis Ex. – when pop goes flat

 In a single displacement reaction, one element takes the place of (displaces) another element in a compound. There are two general forms of the equation ◦ A +BX B + AX ◦ AX +YAY+ X ◦ Ex. Copper and silver nitrate experiment

 Some metals react with water to produce hydrogen gas, while other metals are non reactant. All the alkali metals are able to displace hydrogen from water in exothermic reactions (create energy in the reaction), Such as:

 In a double replacement reaction, the cations or two different compounds exchange places, forming two new compounds  The general equation: ◦ WX + YZ YX + WZ ◦ Ex barium hydroxide + sodium sulfate