CHEM 2211 1nd EditionExam # 1 Study Guide Lectures: 1 - 8Lecture 1 (August 20th)Remembering general chemistry. Important questions: 1.What are the main rules and principles?a. Are any of them related?2.What are the basic types of bonding?3.How are they different?4.What are the types of structures from this lecture?5.Show examples of each and how they are different. 1.What are the main rules and principles?There are 3 principles, and 1 rule. - Quantum number principle - Aafbau’s principle - Pauli principle - Hunds rule 2 of the principles and hunds rule relate to electrons and how to assign them to atomic orbitals Aafbau’s principle: tells us the first step to assigning electrons to orbitals- That an electron always goes into the lowest energy orbital available. - Note: the closer the orbital to the nucleus the lower the energy o S<P<D<F o Also 1S<2S<2P<3S<3P<3d etc…. Pauli exclusion principle: gives us the second piece to placing electrons - No more than two electrons can occupy each atomic orbital - Also the electrons must have opposite spinsHunds rule: last rule to assigning electrons to orbitals- When there are two or more atomic orbitals with the same energy, and electron willoccupy an empty orbital before it will pair up with another electron This can all be represented by doing an electron configuration of an atom Sodium atomic number 11. Orbitals: 1s 2s 2p 2p 2p 3sHunds rule is representing the 2p part of this electron configuration First: 1s 2s 2p 2p 2p the electrons occupy each 2p orbital in the same spin direction firstThen: 1s 2s 2p 2p 2p 3s What are the basic types of bonding? - polar: results from a bond between two nonmetals of different electro negativities - non-polar: results from a bond between two nonmetals but they are the same electro negativities - ionic: bond between a metal and nonmetal where one transfers an electron leaving a charge - covalent : bond that involves the sharing of electrons between atoms could be polar or nonpolar types of structures? There are 3 from this lecture 1. lewis dot : lines are drawn between atoms to show bonds dots are put around atoms to show lone electrons2.Kekule: same basic structure as lewis, lone electron dots are omitted 3.Condensed: no lines to show connections, just atomic symbols put in order Lewis dot structure: H-:C=C:-H Kekule structure: H-C=C-H Condensed structure: CHCHLecture 2 (August 22nd) Important questions1. How do polar bonds relate to polar molecules?2. What are the parts of a perspective diagram? 3. How to draw skeletal structures?a. Why we use them in organic chemistry How do polar bonds relate to polar molecules?A polar molecule has to have polar bonds within it, but not every molecule with polar bonds is apolar molecule. A polar molecule has to have polar bonds and be non-symmetrical, in other words the bonds oneither side of the center molecule cant cancel out. A non-polar molecule is perfectly symmetrical, so the bonds on either side of the center molecule cancel out each other. They have the same electronegativity difference. Parts of a perspective diagrams- Wedges- Dashed wedges - Lines These parts show which plane each atom is in off a center molecule Wedges show atoms coming in front of the center molecule plane Dashed wedges show atoms going behind the center moles plane Lines show atoms in the same plane as the center moleculeHow to draw skeletal structures and why we use them?Skeletal structures are the most condensed and simple structures which is why we use them in organic chemistry. Skeletal structures are just line structures, they omit drawing hydrogens and carbons. Carbons are represented by the points of each line and hydrogens are implied. Anything that’s not a C or H gets drawn in, in its place. This skeletal structure. Is hexane Lecture 3 (august 25th) Important questions1. What is an acid? 2. What is a base?3. What is a strong acid?4. What is a strong base?5. What is pKa?a. How to use pKa to determine equilibrium 6. What is pH?What is an acid?An acid is by basic definition a proton donator. What is a base? A base is a proton acceptor. What is a strong acid?There is a list of strong acids.- HCl- HBr- HI- HClO3- HClO4- H2SO4Anything that is not a strong acid, is a weak acid What is a strong base. Strong bases are found in the first two groups on the periodic table - NaOH- Ca(OH)2- KOH- Etc…. Anything that is not a strong base is a weak base. Weak bases, conjugate acids are very strong acidsStrong bases, conjugate acids are weak acidsAnd vis versa for acids conjugate bases. What is pKa? pKa is the acidity of a given hydrogen atom lower the pKa the more acidic the atom. pKa is determined by the equation –log Ka= pKa - Ka is the acid dissociation constant- If Ka is less than 1 than reactant are predominate at equilibrium - If Ka is greater than 1 than products are predominate at equilibrium What is pH?Measure of acidity, it is measured on a scale from 0-14. - Strong acids are on the lower part of the scale usually between 0-3 - Weak acids between 4-6- Neutral is 7 - Weak bases are 8-11ish- Strong bases are on the higher part of the scale 12-14 Lecture 4-5 (august 27th- 29th)Important questions 1. In order of increasing acidity, what are the main groups of this lecture?2. How do you predict acid base reactions? 3. What factors affect the pKa? Main groups of this lecture. There are four main groups addressed in this lecture- Carboxylic acids - Alcohols- Protonated alcohols- Amines In order of increasing acidity they go - Amines- Alcohols- Carboxylic acids- Protonated alcohols Remember you predict the acidity of a give molecule based on its pKa Greater the pKa less acidity the compound Lower the pKa stronger the acid, more acidic the compound - Amines (pKa 40)- Alcohols (pKa 16ish)- Carboxylic acids (pKa 3-5) - Protonated alcohols (pKa <1) Acid base reactions. pKa is also used to predict an acid base reaction. By looking at the pKa of each reactant in the reaction we can tell which one will be the acid and which one will be the base. The reactant with the lower pKa will act as the acid, an thus the reactant with the high pKa will be the base. From this the reaction can be preformed knowing which reactant will donate and which will accept. Factors affecting pKa. There are 5 factors that affect pKa. 1. Electronegativity 2. Hybridization3. Size4. Inductive substitutes5.