Molecular Geometry: VSEPR model stand for valence-shell electron-pair repulsion and predicts the 3D shape of molecules that are formed in bonding. Sigma and Pi Bonds: All single bonds are sigma(σ), that occur in the overlap of hybridized orbitals. Pi (π) bonds occur when parallel, unhybridized p orbitals overlap. Double bonds contain one sigma and one pi bond; triple bonds contain one sigma and two pi bonds. π bonds are weaker than the σ bonds, but because π bonds are found with σ bonds they are stronger than a single σ bond. Pi bonds also prevent rotation about the bond. Hybridization: Blending of outer bonding orbitals Intermolecular Forces: London Dispersion - Weak intermolecular force, temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. London (dispersion) forces are the forces that cause non-polar substances to condense to liquids and to freeze into solids when the temperature is low. Because of the constant motion of the electrons, an atom or molecule can develop a temporary (instantaneous) dipole when its electrons are distributed asymmetrically. Dipole-dipole - Forces occur between two polar molecules and result from the attractive forces between the positive end of one molecule and the negative end of another. Weaker than ionic or covalent bonds and have an effect only when the molecules involved are close together. Hydrogen bonds - A type of dipole-dipole attraction. The bonds between the hydrogen atom of one molecule and the nitrogen, oxygen or fluorine of another molecule are very short and cause a stronger polar. The attractions between these molecules are particularly strong. Organic Chemistry: Molecules containing carbon, with the exception of carbides (SiC), carbonates (CaCO3), and carbon oxides (CO2). Covalently bonded and allow for unique structures with long carbon chains and rings. Carbon atoms form very stable covalent bonds with one another, known as catenation. Properties of Organic Molecules: They usually have low melting points. They are usually non- polar (unless there are functional groups). Less soluble in water compared to many inorganic salts, except certain compounds, like low weight alcohols and carboxylic acids where hydrogen bonding occurs. Do not Conduct electricity. Exist in most states of matter. Alkanes: Saturated hydrocarbons that corresponds to the formula CnH2n +2, where n is the number of carbon atoms in the molecule. All the members of the series are not reactive. However, they are combustible at high enough temperatures. The first four members of the series are gases at normal temperatures and pressures; intermediate members are liquids; and the heavier members are semi-solids or solids. Naming: Identify the longest carbon chain (Prefix before ane, ene, yne). Place double/triple bond at the lowest carbon position and put the carbon position in the name. if no multiple bond then place the most side chains at the lowest carbon bond, and identify the side chains and the carbon potion and incorporate into naming. Alkenes: Chain of hydrocarbons in which a double bond exists between two carbon atoms. The general formula for the series is CnH2n, where n is the number of carbon atoms. Lower members are gases, intermediate compounds are liquids, and the higher members of the series are solids. These compounds are more chemically active and easily react with substances such as halogens, adding atoms at the double bonds. Alkynes:contain a triple bond between two carbon atoms in the molecule. They are very active chemically and are not found in nature. Follow the formula CnH2n-2 Cyclical Hydrocarbons: a series of carbon atoms are connected together to form a loop or ring. Cyclic structures are more reactive than their linear counterparts. Follow CnH2n. Aromatic Structures: All aromatic compounds are based on benzene, C6H6, which has a ring of six carbon atoms, with alternating double bonded carbon structures, that resonate. Functional Groups: Alcohols: The hydroxyl group (–OH) found in alcohols makes alcohols more soluble in polar solvents than the hydrocarbon from which they were derived and also increases the boiling point due to hydrogen bonding formed between the alcohol molecules. When naming alcohols, remove the ending of the hydrocarbon and replace with “ol” Carboxylic Acids: The functional group of an organic acid is known as a carboxyl group (— COOH). Carboxylic acids are weak acids. To name organic acids, replace the ending with “-oic acid” Amides:Amides are commonly formed from the reaction of a carboxylic acid with an amine which forms peptide bonds between amino acids. Amides can participate in hydrogen bonding as hydrogen bond acceptors and donors, but do not ionize in aqueous solution. Amide formation plays a role in the synthesis of some condensation polymers, such as nylon and Kevlar. For amides with an NH2 group, name the parent carboxylic acid, drop the “–oic acid” and add “– amide”. For amides with a substituted nitrogen, name the alkyl groups attached to the nitrogen, then name the parent acid, drop the “–oic acid” and add “–amide.” Amines: Amines are organic bases. The R groups can be hydrogen atoms or hydrocarbon groups. To name an amine, use the name of the hydrocarbon group followed by “amine” all written as a single word. Aldehydes:Aldehydes contain a carbonyl group (C = O) to which one hydrogen is attached and the carbonyl group must be attached to the last carbon of the chain. To name an aldehyde, add the suffix -al. Keytones: Ketones have a carbonyl group (C=O) attached to an carbon atom. Ketones are commonly used as organic solvents due to their polarity. To name ketones, replace the ending of the molecule with the suffix -one and use a number to indicate the position of the carbonyl group in the molecule. Esters: Esters are commonly formed as the product of a condensation reaction between an acid (usually an organic acid) and an alcohol (or phenol compound). Condensation reactions occur when two molecules are joined together and eliminate a small molecule, e.g., H2O. A condensation reaction to form an ester is called esterification. To name esters, use the name of the group derived from the alcohol followed by the name of the group derived from the acid, end with “-oate” Ethers: Ethers are formed by the condensation reaction between two alcohols. To name ethers, place the names (in alphabetical order) of the two R groups before the word “ether” Isomers: Chain Isomers: Positional Isomers: Functional Isomers: Geometric Isomers: Optical Isomers: enantiomers occur with the creation of non-superimposable mirror images of each other. which only occur when two of the bonds are switched. Polymers Reactions Addition: transformation of a many double bonded molecules into an longer singlebonded carbon chain. Vinyl Chloride -> PVC Condensation: the linking of two monomers together to create a new organic polymer and a waste molecule of water.