Final Exam Study Guide Lectures 1 20 Lecture 1 August 22 Atomic Structure Understand what an atom looks like and where the nucleus protons and electrons are Know subshells s p d f and how to write the electron configuration of an elements o Rules for how electrons are placed in orbitals Aufbau Principle fill lowest energy orbitals first 1s 2s 2p 3s Pauli Exclusion Principle there can only be 2 electrons per orbital and the spins must face the opposite ways one up and one down Hund s Rule add 1 electron to each orbital equal in energy first then go back and add a 2nd electron to these orbitals if there is enough Know how to draw Lewis Dot Structure element surrounded by dots to equal the number of electrons in the valence shellUnderstand the octet rule each element wants 8 electrons so it could have a noble gas configurations Chemical bonds form in an attempt to complete the octet through sharing electrons between atoms Be able to draw atoms bonding by sharing electrons Complete the octet by Losing or gaining electrons CHEM 333 tion 1st Edi Sharing electrons with one or more other atoms covalent bond Lecture 2 August 27 Know the difference between polar and nonpolar bonds o Nonpolar bond where electrons are shared equally o Polar when elements do not share electrons equally need two different ele ments for this to happen Know how to predict polarity o Predict by electronegativty When drawing arrows on elements to show polarity draw arrow going towards the most electronegative element between the two elements that are bonded Understand how to find formal charge o of valence electrons group of electrons in lone pairs 1 2 shared electrons Know how to identify how regions of density and what bond angles result o Regions of electron density include a lone pair single bond double bond or triple bond 4 regions of electrons density angles are 109 5 3 regions of electron density angles are 120 2 regions of electron density angles are 180 Understand resonance structures and how to draw them o Rules for resonance structures All structures must have the same number of electrons electrons cannot just dissappear they must go somewhere All structures must be valid Lewis structures Never more atoms only electrons Double bonds and lone pairs can shift but do not break single bonds Number of paired and unpaired electrons must remain the same Negative charge should go on the more electronegative atom o Rules for deciding resonance structure that is major contributor Filled valence shell octet structure contributes more Maximum number of covalent bonds contributes more Structure with the least separation of unlike charges contributes more Lecture 3 August 29 Understand what s and p orbitals look like Know how electrons act as waves Understand hybridization o Tetrahedral shape 1s 3p sp3 109 5 25 s character o Trigonal planar shape 1s 2p sp2 120 33 s character o Linear shape 1s 1p sp 180 50 s character Lecture 4 September 3 Know how to identify hybridization of each atom This chart can be used for reference of regions bond angle hybridization 1 s 2 180 3 120 sp2 4 109 5 sp3 sp Know how to identify a polar molecule o Must have polar bonds and epends on arrangement of polar bonds A Molecular dipole vector sum of bond dipoles a Examples The more polar something is the greater molecular dipole is 0 when molecule is nonpolar Know what a molecular dipole is o Vector sum of bond dipoles The more polar something is the greater the molec ular dipole is Molecular dipole 0 when molecule is nonpolar Lecture 5 September 5 Be able to identify the following types of hydrocarbons o alkane o alkene o alkyne Be able to identify the following functional groups o alkyl halides o alcohols o ethers o amines o aldehydes o ketones o carboxylic acids o esters o amides o nitriles Understand the difference between ion ion forces dipole dipole forces and hydrogen bonding o Ion Ion Forces Strong electrostatic forces between positive and negative charges Takes high energy to break interaction has a high melting point and has a high boiling point o Dipole Dipole Some molecules are polar and have a permanent dipole They orient so the positive part of one molecule lines with the negative part of another This causes strong interactions with each other o Hydrogen Bonds Strong interaction between heteroatom with H and heteroatom with a lone pair Found with O N and F These bonds are weaker than covalent bonds but stronger than dipole dipole Lecture 6 September 10 Understand dispersion forces o Very weak intermolecular forces of attraction resulting from the interaction be tween temporary induced dipoles o Happen at any time where there can be polarization of electron desnisty because electrons move o Gives a temporary dipole moment that can induce a temporary dipole in a molecule next to it o The attractive force is temporary Know the trends in physical properties o Small vs larger molecules Small molecules less surface area less interaction weaker attraction Larger molecules more surface area more interaction stronger attraction o Boiling points stronger intermolecular interactions increase the boiling point o Solubilities Like dissolves like For example oil dissolves in oil and water dissolves in water Polar and ionic solids usually dissolve in polar solvents Polar liquids are miscible meaning they can mix together Nonpolar solids are soluble in nonpolar solvents Nonpolar solvents are miscible meaning they can mix together Know the difference in hydrophobic and hydrophilic molecules Know the difference in homolytic and heterolytic cleavage Understand how to tell if there something is an acid or a base o Bronsted acid substance that gives up a proton proton donor Acid H H2O Acid H3O o Bronsted base substance that can accept a proton proton acceptor Base H2O Base H OH Know how to tell if it is a strong or weak acid o Measure acidity and get a pKa value Know trends in pKa o Larger pKa weaker acid o Small pKa stronger acid o Weak acid stronger conjugate base o Strong acid weaker conjugate base Memorize these pKa values o C2H6 pKa 50 o pKa 44 o NH2 H pKa 38 o pKa 25 o pKa 16 o HO H pKa 15 7 o pKa 10 o H3N H pKa 9 o H2CO3 pKa 6 o pKa 5 o H3O pKa 1 7 o HCl pKa 7 o H2SO4 pKa 9 o HI pKa 10 Know that equilibrium lies toward the weaker acid Lecture 7 September 12 Know how to determine acidity by looking at electronegativity larger size resonance in duction and hybridization How to determine strongest base o Look at stability Least stable best