org chem chapter 1a.pdf

Organic Chemistry Applications of organic chemistry  Organic Chemistry Chemistry of Carbon (H, O, N, S, Halogens and P). H: 0.9% Ti: 0.6% Others: 0.9% Abun...

Organic Chemistry Applications of organic chemistry  Organic Chemistry Chemistry of Carbon (H, O, N, S, Halogens and P). H: 0.9% Ti: 0.6% Others: 0.9% Abundances of the Elements in the Earth's Crust http://www.webelements.com/shop/product.php/60/periodic_table_shirt_white  Why separate carbon Carbon atoms’ unique ability for bonding - can form chains of thousands of atoms or rings of CH3 OH NO2 1 NO2 Br 1 Br 4 all sizes, which can form 2 6 2 3 branches and cross links 3 5 3 2 4 4 1 Br Cl Br CH2 CH3 4-Chloro-2- 2,4,6-Tribromophenol 2-Bromo-1-ethyl-4- nitrotoluene nitrobenzene  Carbon is TETRAVALENT Carbon can form SINGLE, DOUBLE or TRIPLE BONDS CH2 CH2 CH3 CH3 CH2 C CH2 C CH3 CH3 Organic molecules exhibit ISOMERISM  Organic Compounds Isolation from nature (animal and plant) (extract-isolate-purify) Obtained by: Synthesis in lab Organic compounds: 10 million Inorganic compound: 1.7 million Friedrich Wöhler (1828) O NH 4 Cl + AgNCO heat H2 N-C-NH2 + AgCl Ammonium Silver Urea Silver chloride cyanate chloride Compounds in living systems are organic: Biochemistry Differences between Inorganic and Organic Compounds  ELECTRONIC STRUCUTURE and BONDING CHEMICAL BONDS - the attractive force that holds two atoms together in a more complex unit - forms as a result of interactions between electrons found in the combining atoms  TYPES OF CHEMICAL BONDS 1. IONIC BOND - formed through the transfer of one or more electrons from one atom or group of atoms to another atom or group of atoms - bond present in ionic compounds 2. COVALENT BOND - formed through the sharing of one or more pairs of electrons between two atoms - bond that join molecular compounds  VALENCE ELECTRONS AND LEWIS SYMBOLS VALENCE ELECTRON - an electron in the outermost electron shell of a representative element or a noble gas -the term valence is derived from the Latin word valentia, which means “capacity” (to form bonds) LEWIS SYMBOL - the chemical symbol of an element surrounded by dots equal in number to the number of valence electrons present in atoms of elements - frequently called electron-dot structure  valence The number of valence shell electrons an atom must gain or loss to achieve a valence octet In covalent compounds, the number of bonds which are characteristically formed by that atom is equal to that atom’s valence Three Important generalizations about valence electrons that can be drawn from a study of the Lewis symbols 1. Representative elements on the same group of the periodic table have the same number of valence electrons.( Elements in the same group in the periodic table have similar chemical properties as a result of their similar outer-shell electron configurations) 2. The number of valence electrons for representative elements is the same as the Roman numeral periodic-table group number. 3. The maximum number of valence electrons for any element is eight. Chemical Bonding Chemical Bonding – is the force of attraction between any two atoms in a compound. Lewis Symbols Lewis Symbols (or Lewis Structures) – is a convenient way of representing atoms singly or in combination. -Only the valence electrons are shown  Covalent Bond Between nonmetallic elements of similar electronegativity. Formed by sharing electron pairs Stable non-ionizing particles, they are not conductors at any state Examples; O2, CO2, C2H6, H2O, SiC  Bonds in all the polyatomic ions and diatomics are all covalent bonds Chemical Bonding Ionic Bonding -Metal + Nonmetal Covalent Bonding - Nonmetal + Nonmetal NaCl This is the formation of an ionic bond. + - Na Cl electron transfer and the formation of ions Cl2 This is the formation of a covalent bond. Cl Cl sharing of a pair of electrons and the formation of molecules  More sharing examples O2 Share until octet is complete. O O O O O O double bond (2 pairs) N2 octet complete N N N N N N N N triple bond (3 pairs)  Exercise # 1 Determine the number of valence electrons in atoms of each of the following elements. Write Lewis symbols for each. a. 12Mg b. 14Si c. 33As  CLASSIFICATION OF ORGANIC COMPOUNDS 1. Hydrocarbons a. Aliphatic Hydrocarbon b. Aromatic Hydrocarbon 2. Heteroatoms a. with halogens- Organic halides b. with oxygens- alcohols, phenols, ethers, aldehydes and ketones, carboxylic acids, anhydrides, esters c. With nitrogen – amines d. With oxygen and halogens- acid halides e. With oxygen and nitrogen – amides, amino acids f. With sulfur – thiols, sulfides  FUNCTIONAL GROUPS An atom or group of atoms within a molecule that shows a characteristic set of predictable physical and chemical properties. – A way to classify families of organic compounds. – They determine the chemical and physical properties of a molecule. – They undergo the same types of chemical reactions. – A way to name organic compounds.  Functional Groups Functional group – additional atom or groups of atoms (containing elements in addition to H and C) found on a mostly hydrocarbon molecule  Examples of Functional Groups -OH hydroxyl -COOH carboxyl -NH2 amino -C=C alkene