Organic Chemistry I CHEM 2311 1General Information Lectures: MWF 1:05 -1:55 pm Clough Commons: Room 152 Office Hours: Tuesdays 11-12 am – ES&T 2354 Online platform: Piazza INSTRUCTOR Dr. Pamela Pollet School of Chemistry and Biochemistry ES&T 2372 (404)-385-4484 [email protected] INFORMATION T-square (piazza forum, wileyPlus link, practice homework etc..) TEACHING ASSISTANTS Joshua Hollett [email protected] Allen Winburn [email protected] Enbo Zhao [email protected] TEXTBOOK Solomons organic Chemistry, 11e WileyPLUS.com 2 HOMEWORKS: • Online (wileyplus) –1 week window • Must register your WileyPLUS account (will be valid for 12 months –for this semester and next semester) • 10 homework assignmentsCourse Information EXAMS: • 5 mid-term exams (E1-5) ; 100 points each • Final exam (F) 200 points • The lowest score of mid-exam will be dropped. HOMEWORKS: • 10 homework assignments • Homework counts for 50 points of the total final grade PERSONAL RESPONSE SYSTEM (PRS): • PRS quizzes are to promote participation and is an assessment tool. They will not be graded. FINAL-EXAM EXEMPTION POLICY: • Turned all homework assignments on the due date • Average score of 90 or higher on ALL five mid-term exams • Exempt of final with “A” GRADE: Score (out of 650) = HW + E1 + E2 + E3 + E4 + E5 + F - lowest mid-term score -- 85% (595 points) will guarantee an "A” -- 70% (490 points) will guarantee a "B” - 60% (420 points) will guarantee a "C” -- 50% (350 points) will guarantee a "D" 34Chapter 1 THE BASICS BONDING AND MOLECULAR STRUCTURE • How did Living Organisms Arise? – Abiotic Chemistry – Here at GT: Center for Chemical Evolution (Nasa & NSF) – Miller & Ureys original experiments 5 DNAOrganic Chemistry: The chemistry of the compounds of carbon (1) The human body is largely composed of organic compounds. (2) Organic chemistry plays a central role in medicine, bioengineering, etc. Amoxicillin, Antibiotic (C16H19N3O5S) AZT, AIDS (C10H13N5O4) Fluoxetine, Antidepressant (C17H18F3NO) DDT, insecticide (C14H9Cl5) Polystyrene, polymer 6The Structural Theory of Organic Chemistry Between 1858 and 1861, Kekule, Couper, and Butlerov provided the foundations for structural theory. Central Premises: (1) Valency: atoms in organic compounds form a fixed number of bonds. (2) Carbon can form one or more bonds to other carbons. 7Molecular Formula: C8H8 MW: 104 g/mol Molecular Formula:C8H8 MW: 104 g/mol Cubane, solid Basic structure for fuels Styrene, liquid Polymer precursor CONSTITUTIONAL ISOMERS 8Isomers (1) Isomers are different molecules with the same molecular formula. (2) Many types of isomers exist. Example: Consider two compounds with molecular formula C2H6O. These compounds cannot be distinguished based on molecular formula. However they have different structures. The two compounds differ in the connectivity of their atoms. Constitutional Isomers Constitutional isomers are one type of isomer. They are different compounds that have the same molecular formula but different connectivity of atoms. They often differ in physical properties (e.g. boiling point, melting point, density) and chemical properties. 9In Class Problems: How many constitutional isomers of C3H8O are possible? (1) 2 (2) 3 (3) 5 (4) 1 10Three Dimensional Shape of Molecules Virtually all molecules possess a 3-dimensional shape which is often not accurately represented by drawing. It was proposed in 1874 by van’t Hoff and le Bel that the four bonds around carbon where not all in a plane but rather in a tetrahedral arrangement i.e. the four C-H bonds point towards the corners of a regular tetrahedron (with an angle ~ 109o). 11Three Dimensional Shape of Molecules Consider the constitutional isomers (C2H6O) ethyl alcohol and dimethyl ether: Ethyl Alcohol Dimethyl Ether 12Whenever possible, the valence electrons in a compound are distributed in such a way that each main-group element in a molecule (except hydrogen) is surrounded by 8 electrons (an octet of electrons) Chemical Bonds: The Octet Rule •Covalent Bonds •Ionic Bonds 13Chemical Bonds: The Octet Rule Octet Rule: (1) Atoms form bonds to produce the electron configuration of a noble gas because the electronic configuration of noble gases is particularly stable. (2) For most atoms of interest this means achieving a valence shell configuration of 8 electrons corresponding to that of the nearest noble gas. (3) Atoms close to helium achieve a valence shell configuration of 2 electrons. (4) Atoms can form either ionic or covalent bonds to satisfy the octet rule. Gain electrons Lose electrons 14Ionic Bonds (1) When ionic bonds are formed atoms gain or lose electrons to achieve the electronic configuration of the nearest noble gas; there is a transfer of electrons from one atom to another. (2) The resulting oppositely charged ions attract and form ionic bonds. (3) This generally happens between atoms of widely different electronegativities. Electronegativity: (1) Electronegativity is the ability of an atom to attract electrons. (2) Electronegativity increases from left to right and from bottom to top in the periodic table (noble gases excluded). (3) Fluorine is the most electronegative atom and can stabilize excess electron density the best. 15Ionic Bonds (1) When ionic bonds are formed atoms gain or lose electrons to achieve the electronic configuration of the nearest noble gas; there is a transfer of electrons from one atom to another. (2) The resulting oppositely charged ions attract and form ionic bonds. (3) This generally happens between atoms of widely different electronegativities. Example: Lithium Fluoride (a salt) (1) Lithium loses an electron (to have the configuration of helium) and becomes positively charged. (2) Fluoride gains an electron (to have the configuration of neon) and becomes negatively charged. (3) The positively charged lithium and the negatively charged fluoride form a strong ionic bond (actually in a crystalline lattice). 16Sodium Chloride (Na+Cl-): An Ionic Salt 17Covalent Bonds (1) Covalent bonds occur between atoms of similar electronegativity (close to each other in the periodic table). (2) Atoms achieve octets by sharing of valence electrons. (3) Molecules result from this covalent bonding. (4) Valence electrons can be indicated by dots (electron-dot formula or Lewis structures) but this