Sch4U Final Exam Study Note
Chemistry Exam Study Sheet Organic Chemistry • Study of compounds to which carbon is the principal element. • Carbon is special because it has 4 bonds. Functional Groups • Organic substances are organized into organic families. • Organic Families – group of organic compounds with common structural features. o Each family has a recognizable physical property and a specific structural arrangement. o Each combination is referred to as a functional group. o Even though many functional groups exist, they essentially consist of only 3 main components. ? Carbon- carbon multiple bonds Single bonds between a carbon atom and a more electronegative atom. ? Carbon atom double bonded to an oxygen atom Hydrocarbons • Hydrocarbons are organic compounds that contain only carbon and hydrogen atoms. • There are 3 types of aliphatic hydrocarbons: o Alkanes ? A hydrocarbon with only single bonds between carbon atoms. ? General formula is Cn H2n+2 ? All alkanes have the ending –“ane” ? Any alkyl branches in the carbon chain have the suffix –“yl” ? The name of a branched alkane must indicate the point of attachment of the branch. o Alkenes ? A hydrocarbon that contains at least one carbon – carbon double bond. General formula is Cn H2n o Alkynes ? A hydrocarbon that contains at least one carbon – carbon triple bond. ? General formula is Cn H2n-2 ? In all of these hydrocarbons, the carbon – carbon backbone may form a straight chain, a branched chain or a cyclic structure. ? A hydrocarbon branch that is attached to the main structure of the molecule is called an alkyl group. ? When methane is attached to the main chain of a molecules it is called a methyl group, -CH3 • Prefix of naming hydrocarbons are: o Meth – 1 carbon o Eth – 2 carbon o But – 3 carbon o Pent – 4 carbon o Prop – 5 carbon o Hex – 6 carbon Hept – 7 carbon o Oct – 8 carbon o Non – 9 carbon o Dec – 10 carbon • KEY TERMS TO MEMORIZE o IUPAC – International Union of Pure and Applied Chemistry o Aromatic hydrocarbon – a compound with a structure based on benzene; a ring of six carbon atoms o Isomer – a compound with the same molecular formula s another compound but a different molecular structure. o Cyclic hydrocarbon – a hydrocarbon whose molecules have a closed ring structure. o Aliphatic hydrocarbon – a compound that has a structure based on straight or branched chains or rings of carbon atoms; does not include aromatic compound such as benzene. Aromatic Hydrocarbons o Basically aliphatic hydrocarbons that are attached to benzene. o [pic] o Benzene is a resonating structure (switches back and forth) Reaction of Hydrocarbons • All hydrocarbons readily burn in air to give off carbon dioxide and water. • It also releases large amounts of energy. • Alkanes are usually less reactive than alkenes and alkynes. • This is due to double and triple bonds. • Reaction of Alkanes o The single covalent bonds between carbon atoms are difficult to break. o This makes alkanes rather unreactive. o Will go through combustion reaction if ignited in air. Substitution of Reactions: o A reaction in which a hydrogen atom is replaced by shorter atoms o The halogen atoms used are F2, Cl2 or Br2 (Diatomic compound) o Alkanes go through substituion. o Types: ? Alkane + Halogen ( Organic Halide o This is a substitution reaction by an alkane. • Reaction of Alkanes and Alkynes: o Alkenes and alkynes show greater chemical reactivity due to double and triple bonds. o The reaction of alkanes and alkynes is called an addition reaction. o 4 Types of addition reaction: ? Halogenation (with Br2 or Cl2) • [pic] ? Hydrogenation: [pic] ? Hydrohalogenation (with hydrogen halides) • [pic] ? Hydration (with H2O) • [pic] Reaction of Aromatic Hydrocarbons o The benzene ring does not undergo addition reactions except under extreme conditions. o They go through substitution reactions o Hydrogen atoms are easily replaced. Organic Halides o Group of compounds that include common products such as Freon’s Naming Organic Halides o Consider the halogen atom as an attachment on the parent hydrocarbon chain. o The halogen name is shortened to either fluros, chloros, bromo, or iodo. Properties of Organic Halides: The presence of the halogen atom (ie – Cl) on a hydrocarbon chain makes the molecule polar. o Halogens are more electronegative than carbon and hydrogen o Due to polarity, will have higher boiling points. Naming Alcohols o The –OH functional group is named – ‘Ol’ o The parent alkane is the longest carbon chain to which an –OH group is attached o When an alcohol contains more than 2 carbon atoms abd more than two –OH groups, a number system is used. o Different isomers have different properties o Poly Alcohols: o Alcohols that contain more than one hydroxyl group. o Suffixes are diol and triol. Ethers General formula is R-O-R o There is an oxygen bond to 2 alkyl group which are on either side o Is a bent molecule Naming ethers o Ether is named by adding any to the prefix of the smaller hydrocarbon group. Preparing Ethers from Alcohols o Ether are formed when two alcohols react o Water becomes eliminated o Considered a condensation reaction o Two molecules react to form a larger molecule Controlled Oxidation Reaction o Primary Alcohols o They form aldehydes o Oxidation pan – gain of oxygen or loss of hydrogen o Secondary Alcohols o Will form ketones o Tectiary Alcohols o Don’t go through oxidation. Overall, reactive to the oxygen. Removes 2 hydrocarbon atoms resulting in formation of a C=O group. Aldehydes o This organic compound has a terminal carbonyl functional group. o Ie. R-C-O-H o The carbonyl group always occurs at the end of a parent chain. o These compound are detached over a mile away in various chemical labs because if their distinctive odors. Naming of Aldehydes o When naming aldehydes, drop the “e” from the parent alkane chain and at the ending of “al”. Ketones o Ketones are organic compounds characterized by the presence of a carbonyl group bonded to two carbon atoms.
Naming Ketones o Ketones are named by replacing the “e” ending with an “one” ending. Carboxylic Acids o Carboxylic acids are characterized by the presence of a specific functional group. o Written as –COOH o They are generally weak acids o They have sour tastes Naming Carboxylic Acids o Take the name of the alkane ending off and replace with “OIC” acid o If a carboxylic acid has multiple carboxyl groups, the term “dioic acid” is used. Esters o Occurs naturally in plants o A carboxylic acid reacts with an alcohol to form an ester and water. Naming Esters The name of an ester has two parts o First part is the name of the alkyl group from the alcohol o The second part comes from the acid ? The ending of the acid name changes from “olc” acid to “oate” Amines o Many of the compounds that are naturally produced by living organisms contain nitrogen o When organisms decompose, large and complex molecules such as proteins are broken down to simpler organic compounds called amines o Amines have an unpleasant odor. o In general, thought of as ammonia (NH3) with one, two, or all three of its hydrogen substituted by alkyl groups
Naming Amines o Can be named in either of two ways: o As a nitrogen derivative of an alkane ? aminomethane o As an alkyl derivative of ammonia ? Methylamine Amides o Carboxylic acids react with amononia or with 1( or 2( amines to produce amides. o Types of condensation reaction, ethanoic + ammonia ( ethenamide + water. Polymers o Polymers are large molecules that are made by linking together that have many parts. o The types of small units and linkages can be selected to produce materials with desired properties such as strength and flexibility. Addition Polymers Additions polymers results from the addition reactions of small subunits that contain double or triple carbon – carbon bonds. o These subunits that make up a polymer are called monomers. Properties of Addition Polymers o Plastic are addition polymers that are chemically un-reactive. o This property makes them ideal for use as containers for chemicals. Condensation of Polymers o When monomers join, end to end, to form ester or amide linkage, polymers called polyesters and polyamides are produced. o Polyesters and polyamides result from condensation reactions… where water is also formed as a product.
Properties of Condensation Polymers o Polyamides chain form exceptionally strong fibers. o The strong attractive force between polar groups in polyesters hold the separate polymer chain together, giving them considerable strength. Structures and Properties Intermolecular Bonds o Molecules can be attached to other molecules by weaker forces of attraction. o These weaker forces are called intermolecular bonds o These forces, which are found amongst molecules, are weaker and could easily be broken when the compound melts or boils. o Types of intermolecular bonds are: Dipole – dipole forces ? Occurs between polar molecules o London dispersion forces ? Occurs between polar and non-polar ? These are forces between the electrons in the atoms of a molecule ? The positive side of one molecule is attached to the negative side of the molecule. ? Force only last a second ? Dispersion forces are effective in larger atoms since electrons dispersion is greater. The Bohr Atomic Theory o The modern atomic theory states: o All mater is made up of tiny particles called atoms. o The atoms of one element cannot be converted into atoms of another element. Atoms of 1 element have same properties o Elements combine to form compound. o Rutherford had guessed that the electrons move around the nucleus as planets orbit the sun. o Spectroscopy is a technique tor analyzing spectra o Bohr made two postulates: o Electrons do not radiate energy as the orbit the nucleus. o Each orbit corresponds to a state of constant energy called a stationary state. o Electrons can change their energy only by undergoing a transition from one stationary state to another. Bohr Energy – Level Diagram Atomic # : 15 ( there are 15 protons and electrons
Period # : 3 ( there are 3 energy levels Group # : 15 ( there are 5 valance electrons 3rd energy level – 5e- 2nd energy level – 8e- 1st energy level – 2e- Protons – 15p+ Symbol – P Name – Phosphorous Bohr – Rutherford Orbital Diagrams o Electrons follow a specific order when placed in their orbitals. o The aufbau diagram shows the order that must be followed. o [pic] o The first orbital is the “s” orbital o “s” is spherically symmetrical around the nucleus. o “p” orbital is dumbshell in shape o there are 3 orbitals o there are 5 sets of “d” orbitals o there are 7 sets of “f” orbitals these are present at higher energy levels. Electron Config o Provides the same formation as energy level diagrams o Example: Mg12 : 1s2 2s2 2p6 3s2 o 1 = principal quantum # o s = type of orbital o 2 = # of electrons Pauli Exclusion Principle: o non two electrons in an atom can have the same four quantum numbers, no two electrons in the same atomic orbital can have the same spin, only two electrons with opposite spins can occupy one orbital Hund’s Rule o one electron occupies each of several orbitals of the same energy before a second electrons can occupy the same orbital. Lewis Theory of Bonding Each element has a fixed valence that determines its bonding ability. o Stability of noble gases was due to the number of outer most electrons in the atom. o The ions would in turn be held together by an electrostatic charge, resulting in ionic bonding. VSEPR o Stands for “Valance Shell Electron Pair Repulsion” o Created by Ronald Nyholm and Ron Gillespre o Pairs of electrons in the valance shell of an atom stay as far apart as possible to minimize the repulsion of their negative charges o Only the valance shell of electrons of a central atom are important. o [pic] Thermolchemistry
Key terms: Thermodynamics – the study of energy and energy transfer Thermochemistry – the study of energy involving chemical reactions System – part of the universe that is being studied and observed (reactants & products) Surroundings – everything else in the universe – Universe = system + surroundings – Eu = Esurroundings + Esystem = 0 Surroundings and Systems o Open system: both matter and energy can move in and out o Closed system: matter cannot leave but energy can o Isolated system: neither matter and energy can leave Enthalpy o Enthalpy (symbol: H- unit: joules (J) Total internal energy of a substance at a constant pressure o Chemical bonds are sources of stored energy o Breaking a bond is a process that requires energy o Creating a bond is a process that releases energy Endothermic Reaction: o System absorbs energy o More energy needed to break bonds then released by creating bonds. o Change in enthalpy is positive Exothermic Reactions o System releases energy o More energy released by creating bonds than needed to break bonds o Change in enthalpy is negative Factors Affecting Reaction Rate o Chemical nature of reactants o Concentration of reactants Temperature o Presence of a catalyst o Surface area Ksp (Solubility Product Constant) – the value obtained from the equilibrium law applied to a saturated solution. Electrochemistry o Oxidation – reduction types of reactions o Also called redox reactions o Oxidation – to combine with oxygen (loss of electrons) o Reduction – the formation of a metal from its compound (gain of electrons) o OIL RIG = Oxidation is loss of electrons, Reduction is gain of electrons o LEO GER = Loss of electrons equals Oxidation, Gain of electrons equal Reduction Half Reaction o Are detailed of hypothetical charges. Use to describe redox reactions and to identify oxidizing and reduction agents o Refer to notes on how to solve half reaction equations. The Nature of Acid – Base Equilibrium o Bronsted – Lowry Theory o Acid – base reaction as a chemical equilibrium having both a forward and reverse reaction that involves the transfer of a proton. o An acid is a substance from which a proton can be removed (proton donors) o A base is a substance that can accept a proton (proton accepters) Formaldehyde o [pic] o Organic compound with the formula CH2O. It is the simplest aldehyde, hence its systematic name methanal. – Ortha – Meta – Pera o [pic]