Types Of Chemical Reactions

What are the different types of chemical reactions? What happens when a chemical reaction occurs? While the fundamental law is always followed, matter or energy is never created or destroyed, during all types of chemical reactions there is some sort of chemical change.

1. Synthesis A synthesis reaction is simply the joining of two simple substances to form a complex substance. For example water is the result of the combination of hydrogen gas and oxygen gas. Neither element is created nor destroyed but rather the two are synthesized to form a completely new product.
2. Decomposition While in a synthesis reaction two substances are combined, with a decomposition reaction one more complex substance is divided into two simple substances. Decomposition is the opposite of synthesis. This type of reaction is often endothermic, meaning heat is used to cause the reaction to occur.
3. Single Replacement A single replacement reaction is slightly more complicated. One substance replaces one other substance. The result is a new compound now with a different substance instead of the replaced substance. The replaced substance still exists after the reaction but it is no longer part of the compound.
4. Double Replacement With this type of chemical reaction two compounds yield two new, different compounds. What happens is that two substances switch places. None of the actual elements are lost but two new compounds suddenly exist in the place of two other compounds.
5. Combustion This is a unique chemical reaction that occurs when substances are burned. All the substances in the reaction combine with oxygen. This type of reaction is exothermic, meaning heat is given off. With organic molecules the result is carbon dioxide and water.