2 A chemical reaction is a process in which the physical and chemical properties of the original substances change as new substances with different physical and chemical properties are formed
3 Law of Conservation of Mass During a chemical or physical change, all mass remains the same.Mass is neither created nor destroyed.
4 Parts of a chemical reaction Subscript tells the # of atoms in moleculeCoefficient tells # of molecules in reaction2 H2 + O H2Ocoefficientcoefficientsubscript
5 Parts of a chemical equation Reactant is what goes into a chemical reactionProduct is what results in the reaction2 H2 + O H2Oproductreactantreactant
6 The ease with which atoms will form bonds is its bonding capacity. Capacity to reactThe ease with which atoms will form bonds is its bonding capacity.This capacity is directly related to the electrons and their placement and number within the energy levels.
7 What happens when a chemical reaction occurs? Atoms can form moleculesMolecules can break apart to form atomsMolecules can react with other molecules
8 Balancing Equations Start with the first atom on the reactants side Count the total number of atoms of the element on left and then on the rightAdd a coefficient in front of atom(s) or compounds where necessaryNever change a subscriptGo back through each atom and recheck and/or change until # are equal on both sides of the equation
9 Types of Chemical Reactions SYNTHESIS2 or more substances combineDECOMPOSITIONcomplex substance breaks downSINGLE - REPLACEMENTuncombined element replaces another element in a compoundDOUBLE - REPLACEMENTatoms of 2 compounds replace each other (a flip-flop)
10 synthesisSimple molecules or compounds combine to make a new and more complex substance2 H2 + O H2O
11 decompositionA complex substance breaks down into simpler substances2 H2O H2 + O2
12 single-replacement 2Na + 2H2O 2NaOH + H2 Single element replaces another element within a compound2Na + 2H2O NaOH + H2
13 double-replacementDifferent atoms in two different compounds replace each otherMgCO3 + 2HCl MgCl2 + H2CO3
14 In any chemical reaction: some energy is needed to start the change some energy is involved during the reaction
15 ACTIVATION ENERGY is what is needed to get a reaction started Ex: striking a match
16 Energy involved in the reaction can be either: Exothermic or Endothermic
17 Exothermic ex means out therm means heat energy is released during reactionthe energy in the reactants are higher than the productsEx: fireworks
18 Endothermic endo means in therm means heat energy is absorbed during reactionthe energy in the products are higher than the reactantsEx: chemical ice
19 Kinetics is the study of reaction rates In order to react, atoms must collide.In order for bonds to be broken, formed or reformed, particles must collide at precisely the correct angle with the proper amount of energy.
20 Four factors that influence the collision theory are . . . Rates of Chemical ReactionsThe more collisions, the faster the rate of the chemical reactionFour factors that influence the collision theory are . . .
21 concentration surface area temperature catalysts the amount of reactants presentsurface areaamount of exposed materialtemperaturehigher temperature causes atoms to display more energy & reaction rate is increasedcatalystsincreases speed by decreasing the activation energy needed, but does not enter the reactioncalled enzymes in living organisms