College Chemistry I
College Chemistry I CHEM 1104
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Chem 1104 Chapter 2 Atoms Molecules and Ions LECTURE OUTLINE I Dalton39s Atomic Theorypostulates that predicted the particle nature of matter 1 All matter is made of which are and particles 2 All atoms of a specific element are Atoms of different elements are 3 Compounds are formed by combination of in small number ratios 4 Atoms are not nor in a chemical reaction but are simply to form new substances Some portions of Dalton s postulates were later proven incorrect 11 Law of De nite Proportionsstates that for a specific compound atoms of elements always combine in proportions Water always has HS and O to form Hydrogen peroxide always has HS and O s to form 111 Law of Multiple Proportionsstates that for elements that combine to form two different they have that are related by numbers Carbon monoxide CO versusCarbon dioxide C02 IV Electrical Nature of Matter 1 Matter can possess 2 Electrical charge can be or Lack of electrical charge implies 3 charges 4 charges 5 When and charges are balanced in numbers the result is overall charge V Three Types of Radiation were discovered by experiment Observations amp Conclusions a Gamma rays b Beta El particles c Alpha V particles VI Three Subatomic Particles and their characteristics Particle Mass Mass Electron Proton Neutron VII Thomson39s Cathode Ray Tube Experiment proved the eXistence of the Thomson39s Model of the Atom VIII Rutherford39s Gold Foil Experiment Observations 1 Most Vparticles 2 Some Vparticles were at small angles 3 Some Vparticles were back at sharp angles Conclusions 1 The atom is mostly 2 A small region of the atom must have concentrated there 3 This small concentrated region which he called the must be very It was later proven to consist of as well as the IX The Nuclear Model ofthe Atom X Atomic Number and Mass Number Atomic Number Z tells the number of in the nucleus of an atom also gives the of the element since atoms are neutral it gives the number of as well charges must Examples What element has a Z 53 What is the atomic number for sodium How many protons are in the nucleus of an iron atom A sulfur atom would have how many electrons Mass Number A tells the sum of the number of and that are in the nucleus Nuclear Symbolshows atomic number and mass number for the atom of an element A Z XI Isotopesatoms of the with different Examples Hydrogen has three isotopes Protium Deuterium Tritium Description Nuclear Symbol What s the same What s different More Practice Complete the following table Nuclear Symbol l Atomic No Mass No p Isotope Name I n0 e l uranium23 8 XII The Periodic Table groups or familiesare which contain elements related by similar behavior amp properties labeled 1A 2A 3B etc or as periodsare which reveal periodic repetition of properties Each period involves in properties refered to as lst 2nd 3rd periods etc main group or representative elementsare at leftmost and rightmost of table designat ed as groups transition elementsin center of table between main group sections designated as groups innertransition elementsat lower part of table includes series elements following and series elements following lVlETALLOlDS Special Groups 1 Group 1A elements are known as a Include etc b Very especially with c Group 1A gt Hydrogen gas 2 Group 2A elements are known as a Include etc b React with to form solutions c Ca is most abundant element in earth s crust d Mg is most abundant element in earth s crust 3 Group 4A is worth mentioning because it contains the basis for biological molecules See p 49 for mention amp p 208 for very interesting applications a C eXists as the element in three different forms called b consists of layers of rings that have weak attractions between them c consists of a network with much stronger attractions d is a soccerball shaped molecule with adjacent membered and membered rings 4 Group 6A contains oxygen which also exists as allotropes a Oxygen is a molecule which means it is made up of atoms chemically glued together b Ozone contains atoms in a shape 5 Group 7A is referred to as the a Includes b All exists as molecules c Greek word for because they react with metals and others to form salts such as table salt 6 Group SA is referred to as or gases a Extremely low b Very low XIII Ionic versus Molecular Compounds A Ionic Compoundoverall compound made up of whose charges out Ionic cmpds are held together by attractions due to the of electrons from the atoms to the atoms Ionsa or group of cations charged ions formed from a that has electrons anions charged ions formed from a that has electrons Driving forceOCTET RULE atoms form ions that look like noble gases have 8 electrons due to their stability Examples of CA T I ONS Examples 0fANIONS B Molecular Compoundsa group of two or more atoms held together by outermost electrons called a bond Examples H20 CCl4 Ionic Compounds Molecular Compounds Elements involved What outer e do Components Attraction or quotGluequot Particle description XIV Empirical vs Molecular Formulas Molecular Formula Empirical Formula De nition Examples benzene sucrose glucose water hydrogen peroxide ethanol mercurous chloride CIDEICIEXAM 1 WILL STOP HERElCICICICI XV Naming Compounds and Writing Formulas General Guidelines 1 Elements Use elemental symbol except for diatomic elements H2N202F2C12Br212 Examples Na phosphorus oxygen Elements are 2 Monatomic Ions A Cations are and use element name B Anions are and use element name with ide ending C Use group location to predict charge Group lA 1 Group SA 3 Examples Group 2A 2 Group 6A 2 ion of phosphorus Group 3A 3 Group 7A 1 ion of magnesium Group 4A 44 Group SA 0 ion of selenium 3 Ionic Compounds metal nonmetal39 written first written second A Containing only m0nat0mic ions Cation named first using element name anion named second using element name with quotidequot ending Examples K20 Be3P2 Al3 and 0239 give formula and is named Na and P3quot give formula and is named B Containing transition metal ions or metals that can have several possible charges Some metals can have several possible charges see ion table handout The charge it possesses in a compound must be specified in the name and formula Method A Stock Method Show charge on metal as numerals in parentheses after element name for cation Method B Old Latin Method Some Latin Names Use Latin name for metal lead plumbum Change ending to for higher charge tin stannum Change ending to for lower charge iron ferrum copper cuprum Formula Cation Stock Method Old Latin Method FeCl3 FeC12 PbOg PbO C Containing polyatomic ions cation written first anion written second Polyatomic ions a group of LEARN THESE nitrite ion N02139 nitrate ion No3139 sulfite ion SO32quot sulfate ion SO42quot phosphite ion PO33quot phosphate ion PO43quot hydroxide ion OHl39 carbonate ion C032quot ammonium ion NH41 hydrogen carbonate HCO3139 cyanide ion CNl39 bicarbonate ion chromate ion CrO4239 dichromate ion Cr2 07239 Other polyatomic ions will be provided with appropriate names IN GENERAL for quotrelativesquot or quotpairsquot ending used for ion with lesser O in a quotfamilyquot or quotpairquot ending used for ion with greater O in a quotfamilyquot or quotpairquot Name cation first usually monatomic an exception is the polyatomic ion ammonium ion NH41 Name anion second using appropriate ending quotitequot or quotatequot NOTE Two exceptions to the quotitequot quotatequot endings for polyatomic ions are hydroxide ion OH 139 and cyanide ion CNI39 Examples NaNO3 has Na and N031quot ions C33P032 has Ca2 and P033quot ions NaHCO3 has Na and HCO3139 ions magnesium hydroxide has and ions aluminum sulfate has and ions 4 Acidssubstance which yields when dissolved in water Therefore ALL acids have as the cation If the ANION ends in then the ACID NAIVIE uses a ide gt b ite gt acid c ate gt acid acid F ormula Acid Name Formula Acid Name H2 803 HBI H2 SC HNO3 5 Basessubstance which yields when dissolved in water Therefore bases must contain Note We will define acids and bases on p 111 Ch 4 in a broader sense to include other substances NaOH KOH BaOH2 NH3 6 Hydratesn ionic compounds that have molecules trapped in the crystal these are NOT aqueous D The water can be driven off by heating the solid BaC12 MgSO4 39 7H20 cupric sulfate pentahydrate 7 Molecular compounds nonmetal nonmetal use Greek numerical prefixes with quotidequot ending monol tri 3 penta5 hepta7 nona 9 LEARN di 2 tetra 4 hexa 6 octa 8 deca lO THESE Examples CCl4 N204 disulfur deca uoride phosphorus triiodide stg N20 Considered molecular as a gas considered as an acid when aqueous Chem 1104 Chapter 4 Reactions in Aqueous Solution LECTURE OUTLINE I Solution Terminology Solutiona uniform in appearance 2 or more components transparent separable by physical means Examples Solutesubstance 39 usually present in the amount Solventsubstance the 39 usually present in the amount usually for this class Example Identify the solvent and solute in each of the following descriptions of solutions a 50mg NaCl and 500mg H20 b 30mL ethanol and 5 mL water II The Dissolving Process A Illustrated Solvent H20 Solute NaCl ionic Illustrated NaCl dissolving in H20 B Predicting S01ubilitynot all ionic compounds are soluble in water Use Solubility Rules Soluble in Water Insoluble in Water All salts with Group IA ions NH41 All salts with N031quot C1031quot C1041quot acetate 1011 Most salts with SO42quot except BaSO4 PbSO4 SrSO4 Salts with C11quot Brl39 and 1139 except those containing Ag Hg22 Pb2 Salts with F1quot except those containing Group HA and Pb2 Most salts w 003239 P043 C2042 CrO4239 s239 Most metal hydroxides OHI39 amp oxides 0239 Would the following be soluble or insoluble in water a Na2CO3 b Pbc12 c LiSO4 d CaO III Electrolytes amp N0nelectr01ytes ability to conduct electricity or not depends on presence of particles and of A Strong Electrolytessubstance which exists only as when dissolved in water Are conductors of electricity Soluble compounds and fit into this category B Weak Electrolytessubstance which exists as with a few present Are conductors of electricity are in this catagory C N0nelectr01ytessubstance which exists as when dissolved in water Are conductors of electricity due to lack of and others fit into this category IV Five Types of Reactions 1 Combination Reactionwhen substances combine to form new substance A B gt AB Example 2 Decomposition Reactionwhen substance breaks down into substances AB gt A B Example 3 Single Displacement Reactionwhen an replaces the cation or anion portion of an compound to form a NEW and NEW compound A BC gt AC B A BC gt BA C Examples 4 Double Displacement Reactionwhen two form NEW compounds react to compounds AB CD gt AD CB A Precipitation Reactionwhen a product is formed from mixed aqueous solutions Solubility Rules used to predict ppt Example B Neutralization Reactionwhen an reacts with a to yield and a acida substance which produces when dissolved in water basea substance which produces when dissolved in water Example 5 Combustion Reactionbuming of a substance in the presence of if substance is based it will form and CXHyOZ 02 gt C02 H20 energy Example V OxidationReduction Reactions A De nition 1 In Terms of Oxygen oxidation of oxygen reduction of oxygen oxidizing agentis itself but is responsible for the other substance reducing agentis itself but is responsible for the the other substance Fe203s 3 COg gt 2Fes 3 C02g 2Mgs 02g gt 2Mg0s 2 In Terms of Electrons quotLEO the lion says GERquot How is charge affected 2Aglaq Cults gt 2Agltsgt CW B Determining Oxidation Numbers p 119 1 Elements have an oxidation number of since they are neutral C115 HgU 2 M0nat0mic ions have an oxidation number to their charge Cu2aq 2 3 Halogens are usually unless combined with oxygen or uorine CaC12aq C10139aq 4 H is usually unless written as the anion then it becomes HClOaq CaH2 5 O is usually unless written as a which then has oxidation number H200 H202aQ 6 The algebraic sum of oxidation numbers in a neutral compound must be 7 The algebraic sum of oxidation numbers in a polyatomic ion must be equal to Examples Determine the oxidation numbers for the underlined atoms in the following 3 H031 d Ksz Summary of OxidationReduction b QOK39 9 K2g207 Perspective Oxidation Reduction In terms of oxygen In terms of electrons In terms of oxidation no VI Writing Net Ionic Equations A Precipitation Example PbN032aCl K2CrO4aq gt 1 Predicting Products Balancing 2 Writing Ionic Equation 3 Writing Net Ionic Equation B Neutralization Example MgOH2aq HClaq gt 1 Predicting Products Balancing 2 Writing Ionic Equation 3 Writing Net Ionic Equation C Single Displacement Example AgNOsaq Cus gt 1 Balance Equation 2 Write Ionic Equation 3 Write Net Ionic Equation VII Solution Concentration A Molaritythe ratio of per cmolaiity M Mixing a solution of specific concentration of solution B Ion Concentration If 0222g CaC12 is dissolved in water to make 200mL of solution What is the ion concentration for that solution C Dilution of Solutionstake a certain amount of solution of concentra tion and add to dilute it The number of remains unchanged while the amount of changes Mconc Vconc Mdil Vdil Example What volume in mL of a 075M H2804 solution is needed to make 250mL of a 050M solution Describe how you would make it VIII Titrationan analytical method for determining of a substance typically makes use of an reaction buret of KNOWN concentration of UNKNOWN concentration indicatordye that changes at various ranges phenolphthaleincolorless in acidic conditions pink in basic conditions Calculating Concentration 1 If acid and base react in a 11 mole ratio like HCl NaOH gt NaCl H20 then can use Macid Vacid Mbase Vbase Example on board back of page 2 If acid and base DO NOT react in a 1 1 mole ratio like H2804 2NaOH gt N32 804 H20 then account for using one of two methods Method A Modify Macid Vacid Mbase Vbase to get quotmoles acid moles basequot In balanced reaction 1 mole acid reacts with 2 moles base so to get them equal must mult moles acid X2 2XIVIacid Vacid Mbase Vbase MmolL CR MmolL Method B M known gt moles known gt moles unknown gt M unknown Example A 0263g sample of Na2CO3 required 2835mL of aqueous HCl for titration to the equivalence point What is the molar concentration of the HCl WORK on BOARD Chem 1104 Chapter 3 Mass Relationships in Chem Reactions LECTURE OUTLINE 1 Atomic Massthe of one measured in amu amu 1 Pb atom amu 1 S atom amu Weighted Average Atomic Massmass displayed on the Periodic Table which accounts for various and WtAvgAtmMass abundance 100atomic massisotope 1 abundance 100atomic massisotope 2 abundance 100atomic massisotope 3 etc Example Determine the weighted average atomic mass for oxygen based on the following data Isotope Atomic Mass Abundance 016 159949 amu 99759 O17 169993 0037 018 179992 0204 11 Molecular Massthe of one in amu 1 molecule of C02 amu1 molecule of C12 amu III The Mole Concept 1 dozen of anything of that thing 1 mole of anything of that thing Chemists use the quotmolequot to count particles 1 mole Na atoms atoms of Na 1 mole C02 molecules molecules of C02 1 mole NaCl formula units of NaCl is also called number N Example 35 doz donuts donuts ON BOARD 35 mole H20 molecules H20 BACK OF PAGE N Use N to convert between Moles lt gt Molecules Particles IV Molar MassMM the mass of of a substance MM 1 atom C amu 1 mole C g Example Find the MM of urea NH22CO N X H X 1 Count each element type C X 2 Mult by the mass on periodic tble O X 3 Sum the results TOTAL 4 Units will be in grams for 1 mole MM Use MlVl to convert between Moles lt gt Grams Examples How many moles would be in 225 g of Na2CO3 Given Relation Want How many grams are in 215 mole of CaNO32 Given Relation Want V Cumulative Calculation using MM N Density etc The density of gold Au is 1932 gcm3 What is the volume in cm3 of a piece of gold that contains 26 X 10 24 atoms If the piece of metal is a square with a thickness of 010cm what is the length in centimeters of one side of the piece ON BOARDBACK OF PAGE VI Percent CompositioneXpresses the relative amount of each by mass Element Mass of element X 100 Total mass cmpd Oxalic acid found in rhubarb leaves has the formula H2C204 What is the Composition of each element H C O VII Determining Empirical amp Molecular Formulas How does the empirical formula relate to the molecular formula Example Eugenol is the active component of oil of cloves It has a molar mass of 1642 gmole and is 7314 C and 737 H the remainder is 0 What are the empirical and molecular formulas for eugenol Example Copper metal and sulfur react to form a copper sulfide Cu S gt CuXSy An excess amount of sulfur is heated with Cu in a crucible After the product is formed continued heating drives off extra sulfur Determine the empirical formula from the following data that is collected Mass of crucible 19732 g Mass of crucible and Cu 27304 g Mass of crucible and CuXSy 29214 g of Conservation of Matter Ch2 p37 matter is neither VIII The Law during a chemical reaction it is simply l lOI The mass of all the always equals the mass of all the sodium bicarbonate acetic acid gt sodium acetate carbon dioxide water HC2H302 gt MASS REACTANTS MASS PRODUCTS ATOMS OF EACH ELEMENT ATOMS OF EACH ELEMENT IX Interpretation of a Chemical Equationdecomposition of hydrogen peroxide Kl 2H202 gt 2H20Cg 02 g Molecular Perspective Mole Perspective NOTE Numbers in front of formulas are called and be present for reaction to obey Putting these numbers in the equation is called chemical equations X Balancing Chemical Equationsnecessary for obeying Law of Cons of Mass 1 Balance first start with least common 2 Balance next 3 Leave and til last element that the is done 4 If any coefficients are fractions multiply every coefficient by denominator to get all whole nos 5 Want simplest coefficients possible should not be able to divide all by a common no Practice A AlOH3 HCl gt AlCl3 H20 B Mg3N2 HCl gt MgC12 NH4C1 C C6HJ 02 gt C02 H20 Combustion Reactionalso called a reaction is ALWAYS a 39 evolves and When reactant is C H and sometimes 0 will always produce and D Cngg 02 gt CO2 H2O XI Calculations from Balanced Equations Stoichiometry A Stoichiometric Factor OR Coef cient Relationship CRratio comparing two substances in a reaction based on their relative proportions defined by coefficients Balance SiCl4 Mg gt Si MgCl2 Coefficient Relationships CR I B MoleA lt gt Mole B Calculations Example For the balanced reaction above if 25 mole SiCl4 are reacted how many moles of MgCl2 would be produced Given Want Relation MM CR MM C Grams A gt Moles A gt Moles B gt Grams B Calculations of A of B Example If 100 g Mg reacts how many grams of Si are produced Given Want Relation D Limiting Reactant Concept Illustrated is present in a limited supply while is present in excess supply The amount of is determined by E Limiting Reactant Calculationswhen quantities of both reactants are given one reactant will be in supply While the other will be in Example If 875g SiCl4 is reacted with 1205g Mg how much MgC12 would be produced Which is the limited and excess reactant XII Percent Yieldis a measure of the of a reaction defined as Yield X 100 theoretical yieldthe amount of that can be obtained from a reaction determined by actual yieldthe quantity of product isolated by experiment takes into account during the process Example 29 on p175 Diborane B2H6 is a valuable compound in the synthesis of new organic compounds One of several ways this boron compound can be made is by the reaction 2NaBH4 S 125 gt 13sz g 2Na15 H2 g Suppose you use 1203g NaBH4 with an excess of iodine and obtain 0295g of B2H6 What is the percent yield of B2H6