What is a Chemical Reaction? A process in which new substances with new chemical and/or physical properties are formed. A burning piece of paper (Chemical Reaction): paper ashes, water vapor, and carbon dioxide Dissolving salt in water (No Reaction): Salt + Water
Parts of a Chemical Equation Reactants The substances that you start with. In this case: Sodium and Chlorine Yields This arrow tells you that the reactants become the products through a chemical reaction. Products The substances you end with. In this case: Sodium Chloride sodiumandchlorineyieldssodium chloride Na+ Cl NaCl
Chemical Equations Mg + O 2 MgO H 2 O H 2 + O 2 C 4 H 10 + O 2 CO 2 + H 2 O magnesiumand oxygenyields magnesium oxide waterhydrogenoxygen butaneoxygencarbon dioxidewater
Types of Chemical Reactions Type 1: Synthesis In a synthesis reaction, two (or more) simple substances form a more complex substance. Synthesis: Two Become One A + B AB
Synthesis Example Na + Cl NaCl sodium and chlorine yields sodium chloride
Types of Chemical Reactions Type 2: Decomposition In a decomposition reaction, a complex substance is broken down into two (or more) simpler substances. Decomposition: One Becomes Two AB A + B
Decomposition Example H 2 O 2 H 2 O + O 2 hydrogen peroxide yields water and oxygen
Types of Chemical Reactions Type 3: Single Replacement Reaction In a single replacement reaction, a single element replaces another element in a compound. Single Replacement: Start with one compound, end with a different compound.
Single Replacement Example Zn + HCl H 2 + ZnCl 2 zinc and hydrochloric acid yields hydrogen and zinc chloride
Types of Chemical Reactions Type 4: Double Replacement Reaction In a double replacement reaction, elements from two compounds switch places and form two new compounds. Double Replacement: Start with two compounds, end with two different compounds.