Chemical Reaction Notes

NotesRates of ReactionsTypes of ReactionsBalancing EquationsChemical ReactionsCovalent BondsIonic Bonding ReviewChemical BondingA chemical bond is when two or more atoms or ions are strongly attached to each other.

Ionic Bond electrostatic force holding oppositely charged ions together

Covalent Bond the sharing of electrons between two atoms to hold them together

Metallic Bond a bond found amongst metals where there is a sea of metal ions amid freely floating electrons.Chemical BondingIonic Bond generally between metals and nonmetals

Covalent Bond generally between nonmetals and nonmetals

Metallic Bond formed between metals and metalsIonic Bonding ReviewIon a charged particleAtoms can become charged when they gain or lose electrons.Gain electrons = more negatively chargedLose electrons = more positively charged

Oppositely charged particles are attracted to each other

Periodic Table ShortcutsP.Table Group #12 345678Valence Electrons12345678Ion Formed+1+2+3+4 -4-3-2-1NAGainers and LosersYou can think about different atoms based on how many electrons they will gain or lose. Gainers Elements who need to gain electrons to become happy/stable.Elements in Groups:Losers Elements who lose electrons to become stable.Elements in Groups: Compounds opposites attract!Positive Ions will attract Negative Ions.

A +1 ion will equally bond with a -1 ion.

A +2 ion will equally bond with a -2 ion.

What happens when a +2 ion encounters a -1 ion?

Gainers and Losers Bond together to form ionic compoundsFormation of Ionic Bond

Formation of Ionic Bond

Formation of Ionic Bond

Formation of Ionic Bond

Covalent Bonds

Covalent Bonding?Timmy and Suzy are at their grandmas house and they both have an 8 pack of colored pencils. Timmy is missing his red pencil and Suzy is missing her green pencil. How can they finish their pictures without a full set of their own colored pencils?

Formation of Covalent BondCovalent bonding The mutual attraction and repulsion forces between the protons (+) and electrons (-) hold two atoms together.-++-Reading Covalent BondsFor each atom, there needs to be an EDD

Each line always represents TWO SHARED electronsThis means that BOTH atoms can count them when determining if they are stable/happy.

Each dot that represents a valence electronReading Covalent BondsThe chemical formula is _________.The type of bond is (IONIC or COVALENT).Each bond contains _____electrons. How many electrons are being SHARED total? ________How many electrons are NOT being shared? ______How many bonds are between Br and Br? ______Yes or No: Are each of the atoms happy? (Circle the electrons/bonds if it helps you).Br Br_Steps for making Covalent BondsFigure out how many atoms of each element you need. [Normally given by the formula] Draw the electron dot diagram for each of the atoms separately. Decide how many electrons each atom wants to GAIN to have a full outer energy level! Line up the electrons to get ready to share.For each two electrons that will be shared, replace the dots with a bond (a line). Continue until each is atom happy when you count shared and any remaining valence electrons.OOONONOOOOOOChemical ReactionsVocabulary ReviewPhysical Change A change in size, shape, or state of an object, yet does not change the actual object.

Chemical Change A change from one substance into another with different properties. Evidence includes: changes in color, odor, size, or energy either received or given off.

VocabularyChemical Reaction A process of chemical change occurring when compounds change bonds and creating new, different substances.Chemical Equation the explanation of a chemical reaction using symbols and numbers to show the atoms involved.Reactants Substances that exist before a reaction.Products Substances that are formed from a reaction.

Understanding Chemical EquationsThe point of a formula is to sum up and quickly explain a reaction that would otherwise be too long winded.

The reactants of one molecule of methane and two oxygen molecules produces the products of one carbon dioxide molecule and two molecules of dihydrogen monoxide.

producesCH4 + O2 + O2 CO2 + H2O + H2OReactants Products

Understanding Chemical EquationsCH4 + O2 + O2 CO2 + H2O + H2OReactants Products

is the same equation as 1 CH4 + 2 O2 1 CO2 + 2 H2O

is the same equation as CH4 + 2O2 CO2 + 2H2O

CH4 + 2O2 CO2 + 2H20Reactant SideAtomProduct SideCarbonHydrogenOxygenCounting Atoms in Reactions1144442 + 2 = 6) Are atoms created or destroyed in a chemical reaction?How do you know?

What does the picture on the right represent?

The products balance the reactants. There are exactly the same number of reactant atoms as there are product atoms. Furthermore, the mass on the left equals the mass on the right. Atoms are not created or destroyed. There is exactly the same number of each type of atom in the products as there are in the reactants. 7) In a physical change, like changing state from a solid to a liquid, the substance itself doesnt really change. Explain how is a chemical change different from a physical change?

In a chemical change a new substance with different properties is formed, but in a physical change it only changes size, shape, or state.C3H8 + 5O2 3 CO2 + 4 H2OReactant SideAtomProduct SideCarbonHydrogenOxygenMore Counting Atoms338810106 + 4 = 1 C4H10 + 13O2 8 CO2 + 10 H2OReactant SideAtomProduct SideCarbonHydrogenOxygen481020262616 + 10 = When Balancing YOU CAN NEVER CHANGE THE NUMBER IN THE SUBSCRIPTS. ONLY COEFFICIENTSConservation of MassWhen a chemical reaction happens, no atoms are created or destroyed.

The number of atoms in the reactants ALWAYS EQUALS the number of atoms in the products.

For a chemical equation to be correct, the equation must be balanced.

30Visualizing Equations!HHCVisualizing EquationsCH4 + O2 CO2 + H2O

CH4 + O2? CO2 + H2OHHONot a Real ReactionOHHCVisualizing EquationsCH4 +2O2 CO2 + 2H2O

CH4 + 2 O2CO2 + 2H2OHHOCombustion

OOOHHOOVisualizing Equations H2 + O2 H2O

H2 + O2 H2O?Not a Real ReactionHHHHOOVisualizing Equations 2 H2 + O2 2H2O

2 H2 + 1O22 H2OSynthesis2 H2 + O2 2H2OHHNVisualizing EquationsNH3 N2 + H2

NH3? N2 + ? H2HNot a real reactionHHNVisualizing Equations2NH3 N2 + 3H2

2NH3N2 + 3H2HHHNHDecomposition

Visualizing EquationsZn + H2SO4ZnSO4 + H2HHZnSingle ReplacementZn + H2SO4 + ZnSO4 + H2

SOOOOVisualizing EquationsK2S + HBr? KBr + ? H2SHKNot a real ReactionK2S + HBr KBr + H2SSBrKVisualizing EquationsK2S + 2HBr2 KBr + H2SHKDouble ReplacementK2S + 2HBr 2 KBr + H2SSBrKHBrVisualizing EquationsHCl + NaOH NaCl + H2OHCl + NaOHNaCl + H2OHAcid BaseOClNaHBalancing EquationsMore worked examples are found on the teacher website.N2 + H2 NH3

NH

KClO3 KCl + O2KClOWorked ExamplesNaCl + F2 NaF + Cl2NaClF

H2 + O2 H2O

HOWorked ExamplesWhat is a chemical change?A chemical change is when a new substance with different properties is formed from the reaction of the REACTANTS.Types of ReactionsSynthesis: (Building something)A+B ABExample2H2 + O2 2H2OEnd with 1 Product

Decomposition: (Destroying something)AB A +B Example2NH3 N2 + 3H2Begin with 1 ReactantTypes of Reactions3. Single Replacement: AX + B A + BXExample2K + MgBr2 2KBr + MgSwitch one partner

4. Double Replacement:AX + BY AY + BXExample 2 AlBr3+ 3 K2SO4 6 KBr + Al2(SO4)3Switch both PartnersTypes of Reactions5. Acid Base: Make a Salt and WaterAOH + HB AB + H2OExample NaOH + HCl NaCl + H2O

6. Combustion:Make CO2 and WaterCxHy + O2 CO2 + H2OExample CH4 + 2O2 CO2 + 2H2O

HHHHOOVisualizing Equations2 H2 + 1O22 H2OHHHHOOVisualizing Equations4 H2 + 2 O24 H2OHHHHOOHHHHOOVisualizing Equations6 H2 + 3 O26 H2OHHHHOOHHHHOOHHHHOOLimiting Reactants6 H2 + 2 O24 H2O + 2H2HHHHHHHHOOHHHHOOLimiting Reactants6 H2 + 1 O22 H2O + 4H2HHHHHHHHOOCCHHHHOOCHONa1 C2H2O2 + 1NaHCO31 NaC2H3O2 + 1CO2 + 1H2OHeat ReactionsExothermic in these types of chemical reactions, heat is given off in the process.Example: Burning Substance combines with Oxygen to form heat, Light, CO2 or Water. (Combustion)Temperature of products rises.

Endothermic in these types of chemical reactions, heat is absorbed in the process.Example: A cold pack that dissolves a solution in water takes in heat from surrounding environment.Temperature of products lowers.Exothermic Reaction in which heat energy is released. Exo means outside. Energy is released to the outside. Example: Burning Substance combines with Oxygen to form heat, Light, CO2 or Water. (Combustion)The Energy of products is lower than reactants, but the temperature of products is higher than reactants (with the excess heat generated)

Reaction ProgressExothermic ReactionReleases energyEnergy of products is lower than reactants. Endothermic Reaction in which heat energy is absorbed.Endo means in. Energy goes IN to the reaction. Example: A cold pack that dissolves a solution in water takes in heat from surrounding environment.The Energy of products is higher than reactants, but the temperature of the reactants is lower due to the absorbed energy.

EndoEndothermic Reaction

Absorbs energyEnergy of products is higher than reactants. Reaction ProgressExo or endo? Reaction ProgressEnergyExo or endo? Reaction ProgressEnergyPutting it all together! Remember Types of Reactions? S = Synthesis:A + B ABD = Decomposition:AB A + BSR = Single Replacement:AX + B A + BXDR = Double replacement:AX + BY AY + BXC= Combustion CxHy + O2 CO2 + H2O

Exo or Endo?

Reaction ProgressEnergy What type of reaction is this? C3H8 + 5O2 3CO2 + 4H2OcombustionExo or Endo?

Reaction ProgressEnergy What type of reaction is this? 2H2 + O2 2H2OsynthesisExo or Endo?

Reaction ProgressWhat type of reaction is this? 2AlBr3+3K2SO4 6KBr + Al2(SO4)3Double replacement Exo or Endo?

Reaction ProgressWhat type of reaction is this? 2NaCl + F2 2NaF + Cl2Single replacement Exo or Endo?

Reaction ProgressEnergy What type of reaction is this? 2KClO3 2KCl + 3O2decompositionRates of ReactionsTemperature When temperature is increases, molecular speed is increased, making reactions happen faster. If you slow down the speed (decrease temperature) then the reaction slows down as well.Temperature Up = Reaction Rate Up

Concentration The amount of substance in a given amount of volume. The higher the concentration, the faster the reaction because the molecules are closer together.Concentration Up = Reaction Rate Up

Surface Area the amount of the substance that is exposed increases the reaction rate because only outer molecules can actually react.Surface Area Up = Reaction Rate UpActivation Energy The minimum amount of energy needed to start a reaction.

Inhibitor Slows down reactions. Chemicals on cereal boxes slowing down the spoiling of foods.

Catalyst speeds up reactions without being used up in the process.

Enzymes Proteins that speed up reaction in your body

Activation Energy The amount of energy needed to start a reaction. The hill in the diagrams. You have to climb the hill before the reaction can start.

Catalyst Speeds up reactions without being used up or changed in the process. Lowers the activation energy of a reaction. It lowers the hill! (Analogy: Like a matchmaker setting up a couple.)

Would you rather be a catalyzed or uncatalyzed reaction?

Which do you think occurs more easily?

Is this exo or endothermic? c

A catalyst lowers the Activation Energy (the hill!) Catalysts you have heard about!Enzymes = Your bodys catalysts! Ex. Enzymes in your saliva help food be broken down FAST!

Can a person act like a catalyst?

A catalyst is a person who gets something started or speeds something up (MLKs speech, starting a club, a starting a winning streak on a sports team, etc).

taken from http://www.americanrhetoric.com/speeches/mlkihaveadream.htmnull352506.0