2 Combination (Synthesis) Reactions Two or more substances combine to form a new compound.A + X AXReaction of elements with oxygen and sulfurReactions of metals with HalogensSynthesis Reactions with OxidesThere are others not covered here!
3 Decomposition Reactions A single compound undergoes a reaction that produces two or more simpler substancesAX A + XDecomposition of:Binary compounds H2O(l ) 2H2(g) + O2(g)Metal carbonates CaCO3(s) CaO(s) + CO2(g)Metal hydroxides Ca(OH)2(s) CaO(s) + H2O(g)Metal chlorates 2KClO3(s) 2KCl(s) + 3O2(g)Oxyacids H2CO3(aq) CO2(g) + H2O(l )
4 Single Replacement Reactions A + BX AX + BBX + Y BY + XReplacement of:Metals by another metalHydrogen in water by a metalHydrogen in an acid by a metalHalogens by more active halogens
5 The Activity Series of the Metals LithiumPotassiumCalciumSodiumMagnesiumAluminumZincChromiumIronNickelLeadHydrogenBismuthCopperMercurySilverPlatinumGoldMetals can replace other metals provided that they are above the metal that they are trying to replaceMetals above hydrogen can replace hydrogen in acids.Metals from sodium upward can replace hydrogen in water
6 The Activity Series of the Halogens Halogens can replace other halogens in compounds, providedthat they are above the halogen that they are trying to replace.FluorineChlorineBromineIodine2NaCl(s) + F2(g) ???2NaF(s) + Cl2(g)MgCl2(s) + Br2(g) ???No Reaction
7 Double Replacement Reactions The ions of two compounds exchange places in an aqueous solution to form two new compounds.AX + BY AY + BXOne of the compounds formed is usually a precipitate, an insoluble gas that bubbles out of solution, or a molecular compound, usually water.
8 Combustion ReactionsA substance combines with oxygen, releasing a large amount of energy in the form of light and heat.Reactive elements combine with oxygenP4(s) + 5O2(g) P4O10(s)(This is also a synthesis reaction)The burning of natural gas, wood, gasolineC3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g)