Wavelength and Energy - Summary General Chemistry

FINAL EXAM REVIEW WAVELENGTH AND ENERG Y Wavelength and frequency are related through the following equation 𝑐=𝜆⋅𝑣 c= speed of light at 3.00x108 𝜆= wavelength in nm V= frequency in Hz To find the energy we use the following equation: 𝜀=ℎ⋅𝑣 𝜀= Energy in Joules h= Planck’s constant 6.63x10-34 v= frequency in Hz QUANTUM NUMBERS Principle Quantum number (n): The principle Quantum number represents the main energy level of an atom’s electrons by a number (1,2,3….) or letter (K, L, M, N….) increasing values of n indicates an increasing value of energy Angular Momentum (l): tells us the shape of the orbitals each value is associated with a different shape. l=(n-1) l=0=spherical=s l=1=dumb-bell=p l=2=clover-like=d Magnetic Quantum Number (ml): determines the number of permitted orbitals in any group. This number ranges from +l to -l Spin Quantum Number (ms): limits the number of electrons per orbital. Only two values are possible: -1/2 and +1/2 Pauli Exclusion Principle: no two electrons can have the same set of all four quantum numbers Hund’s Rule: Electrons must be distributed in orbitals to yield maximum number of unpaired electrons REMEMBER COPPER AND CHROMIUM (ONE AWAY FROM FULL OR HALF FULL D ORBITAL) ARE DIFFERENT! THEY HAVE A FULL 4S ORBITAL! ATOMIC TRENDS Isoelectronic: Atoms with the same electron configuration but different ion (Na+ and Ne) Diamagnetism: not attracted to or slightly repelled by magnetic field (all electrons are paired) Para magnetism: attracted by magnetic fields from unpaired electrons. The more unpaired electrons, the higher the magnetism value. Size and Charge of Ions positively charged ions are smaller, negatively charged ions have a larger radius. MOLECULAR GEOMETRY AND HYBRIDIZATION Molecular Geometry: general shape of a molecule as determined by the relative positions of the atomic nuclei. VESPR Theory: predicts the shape of molecules based on the assumption that valence shells are positioned so the electrons will be as far away as possible from each other. Formal Charges: the charge on each individual atom based on their charge on the periodic table and how many electrons they own in the compound. Hybridization and geometry Linear Trigonal planar Tetrahedral Trigonal Bipyramidal Octahedral AB2 AB3 AB4 AB5 AB6 sp sp2 sp3 sp4 sp5 Sigma Bonds: single bonds Pi Bonds: double and triple bonds. STOICHIOMETRY ALAWAYS USE MOLES For Solids: #𝒎𝒐𝒍𝒆𝒔 = 𝒎𝒂𝒔𝒔(𝒈) 𝑴𝒐𝒍𝒂𝒓 𝑴𝒂𝒔𝒔 For Liquids 𝑪𝒐𝒏𝒄𝒆𝒏𝒕𝒓𝒂𝒕𝒊𝒐𝒏 = 𝒏𝒖𝒎𝒃𝒆𝒓 𝒐𝒇 𝒎𝒐𝒍𝒆𝒔 𝒗𝒐𝒍𝒖𝒎𝒆 (𝑳) and therefore, 𝒏 = 𝒄𝒐𝒏𝒄𝒆𝒏𝒕𝒓𝒂𝒕𝒊𝒐𝒏 𝒙 𝒗𝒐𝒍𝒖𝒎𝒆 For Gases PV=nRT To find the number of moles for a multi-step reaction: • • • • Find a product in the first equation that is a reactant in the second equation Solve for the number of moles of the product in the first equation Use that same number of moles to find the number of moles of the desired product LIMITING REAGENT AND PERCENT YEILD To find the LIMITING REAGENT: 1. Convert the masses you are given into moles using the molar mass 2. Take note of the reaction coefficient 3. Divide the number of moles you calculated by the reaction coefficient. 4. The number with the SMALLEST number of moles, is the limiting reagent. To find the PERCENT YEILD: 1. Use the actual yield given in the question % 𝑌𝑖𝑒𝑙𝑑 = 𝑎𝑐𝑡𝑢𝑎𝑙 𝑦𝑖𝑒𝑙𝑑 𝑡ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑦𝑖𝑒𝑙𝑑 𝑥100 2. Calculate the theoretical yield using the limiting reagent 3. Plug the numbers into the formula CHEMICAL REACTIONS Electrolyte Solutions: Strong electrolyte: The solution exists entirely as ions. This can be salts, STRONG acids and STRONG bases. Weak electrolytes: Solution is partially ionized. This can be weak acids and weak bases Non-electrolytes: Solutions that do not contain ions. (mostly organic compounds) The equations: Molecular equations: the equation in which the products and reactants are written as compounds rather than ions. Complete Ionic Equation: chemical equations in which the compounds are written as individual ions in the solution. Net Ionic Equation: the complete ionic equation with spectator ions cancelled. Precipitate Reactions: A precipitate will form when: There is a compound in the products that is insoluble. ACIDS AND BASES Arrhenius Acid: supplies H+ Arrhenius Base: supplies HO Bronsted-Lowry Acid: Gives an H+ (proton donor) Bronsted-Lowry Base: Receives an H+ (proton acceptor) Strong Acids: acids that FULLY dissociate in water. There are only 6: HCl, HI, HBr, HNO3, HClO4, H2SO4 Strong Bases: Bases made with OH and an alkali metal or alkali earth metal. (Group 1 or 2) Weak Acid: Every other acid you can think of Weak Base: Every other base you can think of, but also the conjugate base of a weak acid EQUILIBRIUM [𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑠]𝑟𝑒𝑎𝑐𝑡𝑖𝑜𝑛 𝑐𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡 𝐾𝑐 = [𝑟𝑒𝑎𝑐𝑡𝑎𝑛𝑡𝑠]𝑟𝑒𝑎𝑐𝑡𝑖𝑜𝑛 𝑐𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡 But remember! Pure solids do not enter this equation! When Kc is very large: reaction goes to completion and the products are favoured. When Kc is very small: reaction favours the reactants. If we reverse a reaction, the K value gets inverted and becomes 1/K . Q is calculated using the Kc equation ACIDS AND BASES (AGAIN!) Lewis Acid: Accepts a pair of electrons for the Lewis Base Lewis Base: gives a pair of electrons to the Lewis Acid. 𝒑𝑯 = −𝐥𝐨 𝐠[𝑯𝟑 𝑶+ ] 𝒑𝑶𝑯 = −𝐥𝐨 𝐠[𝑶𝑯− ] 𝟏𝟒. 𝟎𝟎 = 𝒑𝑶𝑯 + 𝒑𝑯 WHEN YOU HAVE 2 SIG FIGS IN THE CONCENTRATIO YOU HAVE 2 DECIMAL PLACES IN THE pH! 𝒑𝑲 = −𝐥𝐨 𝐠[𝑲] 𝑲 = 𝟏𝟎−𝒑𝑲 Amphoteric: it can act as either an acid or a base depending on the situation. WATER DOES I Because water is Amphoteric it can self dissociate, or self ionize. And pure water contains equal amounts of H3O+ and OH-. Kw=1.00x10-14 =(Ka)(KB) When finding the stoichiometric concentration of Acids and Bases • In a Strong Acid the Nominal concentration is the same as the concentration of H 3O+ • Strong Bases are different because sometimes you have 2 moles of OH- (ex. Ca (OH)2) o In this case you will multiply the nominal concentration by the coefficient (for Ca (OH)2 you would multiply it by 2. • Weak Acids do not fully dissociate in water, so their concentration is calculated by using 𝐾𝑎 = • 𝑥2 𝑁𝑜𝑚𝑖𝑛𝑎𝑙 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛−𝑥 where x=[ H3O+ ] Weak Bases do not fully dissociate in water, so their concentration is calculated in a similar way 𝐾𝑏 = 𝑦2 𝑁𝑜𝑚𝑖𝑛𝑎𝑙 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛−𝑦 where y= [OH-] In both the calculation for concentrations of weak acids and of weak bases you can use approximation instead of using the quadratic formula! 𝑵𝒐𝒎𝒊𝒏𝒂𝒍 𝒄𝒐𝒏𝒄𝒆𝒏𝒕𝒓𝒂𝒕𝒊𝒐𝒏 ≫ 𝟏𝟎𝟎 𝑲𝒂 𝒐𝒓 𝑲_𝒃 In Weak Acids: • A larger Ka means a stronger weak acid • A smaller Ka means a weaker weak acid • pKa= -log [Ka] In Weak Bases: • a larger Kb means a stronger weak base • a smaller Kb means a weaker weak base • pKb= -log [Kb] Determining the Keq of a reverse reaction: • Flip the reaction and see if you can find a Ka or Kb value for the reaction • If you can, the new Keq is equal to 1/Ka or Kb that you found. BUFFERS What is a buffer? • • • A mixture of conjugate base and a weak acid A mixture of conjugate acid and a weak base Must be in a ratio of 0.1 to 10 Calculating the pH of a buffer solution • 𝑝𝐻 = 𝑝𝐾𝑎 + log ( 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑏𝑎𝑠𝑒 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑎𝑐𝑖𝑑 ) Henderson-Hasselbach Equation And therefore the 𝒑𝑯 = 𝒑𝑲𝒂 ± 𝟏 Adding Acid Adding Base: TITRATION CURVES Equivalence Point: The number of moles of acid added is equal to the number of moles of base End Point: When the solution changes colour during a titration. Indicator that is chosen should produce a colour change that is as close to the equivalence point as possible usually within pKa that is ±1 of the pH at equivalence point. How to read titration curves: This is a Strong Acid being titrated with a Strong Base Why? pH at equivalence point is 7, and the starting pH is low like an acid This is a Strong Base being titrated with a Strong Acid Why? pH at equivalence point is 7, and the starting pH is high like a base This is a Weak Acid being titrated with a Strong Base Why? pH at equivalence point is not 7, and the starting pH is low like an acid This is a Weak Base being titrated with a Strong Acid Why? pH at equivalence point is not 7, and the starting pH is high like a base Major Species in the Titration: • • • • At 0ml of titrant o The only species is whatever you started with In the Buffer region o Weak Acid and Weak Base (they make up the buffer) o Ion that is attached to the titrant (in NaOH it would be Na) At equivalence point o Either weak acid or weak base (depending on what you started with) **** opposite of what you started with***** o The ion that is attached to the titrant Past the equivalence point o Either weak acid or weak base (depending on what you started with) **** opposite of what you started with***** o The ion that is attached to the titrant o Excess H3O+ or OH- depending on if you are adding acid or base NAMING ORGANIC COMPOUNDS Alkanes: single bonded long chains of carbon. They are named after the parent (longest chain) of carbons. THIS CHAIN DOES NOT HAVE TO BE A STRAIGHT LINE! Number of carbons in parent chain Name of the Alkane 1 Methane 2 Ethane 3 Propane 4 Butane 5 Pentane 6 Hexane 7 heptane 8 Octane 9 Nonane 10 Decane These chains may have substituents (carbons that branch off the parent chain). They are also named after the number of carbons that are extending off the chain. Number of carbons in the substituent Name of the substituent 1 Methyl 2 Ethyl 3 Propyl 4 Butyl **** but there are special ones! Isopropyl T-butyl These substituents are named with numbers in front of them to give their location. ALWAYS MAKE THIS NUMBER AS LOW AS POSSIBLE BY STARTING AT THE APPROPRIATE END Cycloalkanes: carbons arranged in a ring with only single bonds, in this case the substituents are not numbered unless there is more than one. Alkenes: have double bonds and are named in the same way, with a number indicating where the double bond is Alkynes: have triple bonds and are named in the same way, with a number indicating where the triple bond is Aromatic Hydrocarbons: They are named according to the names above and the substituents are named according to the following chart Location Name and abbreviation 1,2 “o” or Ortho 1,3 “m” or meta 1,4 “p” or para Organic Halogen Compounds (Alkyl Halides): hydrocarbons with halogens as substituents. They are classified as primary, secondary or tertiary based on the carbon that it is attached to. There are 4 options: Halogen Name F Fluoro- Br Bromo- Cl Chloro- I Iodo- Ethers: carbon group- oxygen -carbon group. They are named as two substituents on either side of the oxygen and contain “oxy” in the middle. Alcohols and Phenols: hydrocarbons where an H is substituted with an OH. In order to name it you must identify the longest chain of carbons that includes the OH group. Then number the OH group, and change the “-ane” to an “-anol” Amines: derivatives of ammonia, and characterized as primary, tertiary or secondary based on the carbon that they are attached to. ACIDIC IN NATURE. To name them, locate where the nitrogen is and assign a number to locate it. Then change the “-e” to “-amine” Aldehydes: consist of a carbonyl group (double bonded oxygen) in the end of the chain. To name them, replace the “-e” with an “-anol”, and make sure that the carbonyl group is in the #1 location. Ketones: consist of a carbonyl group in the middle of the chain. To name them you must replace the “-e” with – “anone”. Name this based on the orientation that will give the carbonyl group the lowest number. Carboxylic Acids: contains a carboxylic acid group (carbon double bonded to oxygen and single bonded to OH. To name them replace the “-ane” with “-anoic acid Esters: replaces the H in OH of a carboxylic acid with another carbon chain. To name them, it is based on the oxygen that divides the two carbon groups, and is named by making both carbon groups substituents and adding “-anoate” on the end Amides: Carbonyl group attached to a nitrogen group. In order to name them you must change the “-e” to “-anamine” ORGANIC CHEM Primary/Secondary/Tertiary Carbons: determined based on the number of carbons that attached to the carbon of interest. 1- primary, 2-secondary, 3- tertiary Primary/secondary/tertiary Hydrogens: determined based on how many hydrogens are attached to the carbon. If there are 3- primary hydrogen, 2-secondary hydrogen, and 1 tertiary hydrogen. Structural or Constitutional isomers: structures that have the same chemical formula but different arrangements. Geometric Isomers: when there is a double or triple bond involved, the molecule cannot rotate freely, causing more isomers. They can exist into two spatial arrangements: Chiral Carbons: have the ability to interact with polarized light. They are most commonly characterized by having 4 different groups attached to them (they can also have only 3) A chiral carbon CANNOT be double bonded. They can also be called enantiomers! Intermolecular Forces: decide the physical properties of the chemical compound. London Forces: the weakest of forces, but every compound has them. It is based on partial charges. Dipole-Dipole: Happen when there is a large difference in electronegativity (the molecule is polar) These are stronger than London forces, but are not the strongest forces. Hydrogen Bonding: happen when there is a very large difference in electronegativity. Usually apparent with O, F and N bonding to carbons. These are the strongest forces. Boiling Points/Water Solubility and Intermolecular Forces: The stronger the intermolecular forces the higher the boiling points and the more soluble the compound is. Electrophiles: “loves electrons” therefore is positive and looking for electrons to accept. Often attracted to double and triple bonds! Nucleophile: “loves the nucleus/protons” negative species that is looking to give electrons to a positive species. Free Radicals: a neutral species that has an unpaired electron. ORGANIC CHEM REACTIO NS The only reaction with alkanes is a Free Radical Halogenation Reaction in which a halogen will replace a tertiary carbon in the presence of heat or UV light. However, when there is more than one carbon on the chain the halogen is most likely to replace the tertiary hydrogens than secondary or primary. Reactions with Alkenes and Alkynes: Electrophilic Additions: an electrophile attaches itself to one of the carbons involved in the double bond (which one? The one with the least carbons attached) and then the nucleophile will attach to the other one to balance out the orbits. Hydrogenation: two hydrogen are added to the same side of the double bond in the presence of a catalyst. This same principle applies to add a halogen as well! Polymerization: a monomer reacts with an initiator to form a long chain of identical monomers (polymer). Haloalkanes (alkyl halides): These hydrocarbons are prone to attacks by nucleophiles because of the large difference in electronegativity. The halogens are replaced by a nucleophile, which causes a Nucleophilic Substitution. Aromatic Substitutions: The same as alkyl halide substitutions but aromatic compounds are extremely stable, and therefore in order for this reaction to take place, it must be in the presence of a strong catalyst. Alcohols and Phenols: remember that alcohols are very weak acids, and therefore will only react with VERY strong bases. Probably not on the exam…. Oxidation of Alcohols: using potassium or sodium dichromate, this reaction converts alcohols to carbonyl groups (aldehydes or carboxylic acids). This reaction depends on whether the alcohol is primary, secondary or tertiary. Aldehydes and Ketones: because of the presence of a carbonyl group, these compounds are prone to attacks from electrophiles and nucleophiles. Reductions: addition of H2 to form an alcohol from an aldehyde or ketone. Nucleophilic Addition: because of the double bond nucleophiles are really attracted to aldehydes and ketones. This reaction will break the double bond and add another oxygen while creating an OH out of the existing one. Acid anhydride and an alcohol: the hydrogen in the OH of the alcohol reacts with the carbon attached to the oxygen in the anhydride, creating a carboxylic acid and an ester. Direct Esterification: when an acid and an alcohol combine to make an ester and water. The alcohol will split into its nucleophile and electrophile and then remove the OH from the alcohol to make water. Preparation of an Amide: done by adding an amine and an ester together to create amide and an alcohol. Condensation of Polymers (polyester): The di carboxylic acid is condensed with a diol. In the end the polymer will contain the same number of monomers as there are H-OH’s Condensation of Polymers (polyamide): using a diamine and a diester, the polymer is condensed to the number of H-OCH3’s