PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 471Functional Groups•A functional group is an atom or a group of atoms with characteristic chemical and physical properties. It is the reactive part of the molecule.•Most organic compounds have C—C and C—H bonds. However, many organic molecules possess other structural features:Heteroatoms—atoms other than carbon or hydrogen. Bonds—the most common bonds occur in C—C and C—O double bonds.These structural features distinguish one organic molecule from another. They determine a molecule’s geometry, physical properties, and reactivity, and comprise what is called a functional group.Introduction to Organic Molecules and Functional Groups2•Heteroatoms and bonds confer reactivity on a particular molecule.Heteroatoms have lone pairs and create electron-deficient sites on carbon. Bonds are easily broken in chemical reactions. A bond makes a molecule a base and a nucleophile.Don’t think that the C—C and C—H bonds are unimportant. They form the carbon backbone or skeleton to which the functional group is attached.3•Ethane: This molecule has only C—C and C—H bonds, so it has no functional group. Ethane has no polar bonds, no lone pairs, and no bonds, so it has no reactive sites. Consequently, ethane and molecules like it are very unreactive.•Ethanol: This molecule has an OH group attached to its backbone. This functional group is called a hydroxy group. Ethanol has lone pairs and polar bonds that make it reactive with a variety of reagents.The hydroxy group makes the properties of ethanol very different from the properties of ethane.4Hydrocarbons are compounds made up of only the elements carbon and hydrogen. They may be aliphatic or aromatic.5OHH2SO4OHH OSO3HOH2+ HSO4H2SO4H3C CH3No ReactionOHNaHOHNa HO+ H2NaNaHH3C CH3No Reaction6•Aromatic hydrocarbons are so named because many of the earliest known aromatic compounds had strong characteristic odors.•The simplest aromatic hydrocarbon is benzene. The six-membered ring and three bonds of benzene comprise a single functional group.•When a benzene ring is bonded to another group, it is called a phenyl group.789Compounds Containing the C=O Group:•This group is called a “carbonyl group”.•The polar C—O bond makes the carbonyl carbon an electrophile, while the lone pairs on O allow it to react as a nucleophile and base.•The carbonyl group also contains a bond that is more easily broken than a C—O bond.10It should be noted that the importance of a functional group cannot be overstated.A functional group determines all of the following properties of a molecule: Bonding and shape Type and strength of intermolecular forces Physical properties Nomenclature Chemical reactivity11Which of the following is an aldehyde?H3CH2CH2COCH3H3CH2CH2COHH3CH2CH2COOHH3CH2CH2COCH3ABCDH3CH2CH2COHB12Which of the following is an ester?H3CH2CH2COCH3H3CH2CH2CONH2H3CH2CH2COOHH3CH2CH2COABCDOCH3H3CH2CH2COCOCH313Which of the following is an amide?H3CH2CH2COCH3H3CH2CH2CONHH3CH2CH2COOHH2NABCDOCH3CH2CH3H3CH2CH2CONHBCH2CH3H2NCOCH314Intermolecular Forces•Intermolecular forces are interactions that exist between molecules. Functional groups determine the type and strength of these interactions.•There are several types of intermolecular interactions.•Ionic compounds contain oppositely charged particles held together by extremely strong electrostatic inter-actions. These ionic inter-actions are much stronger than the intermolecular forces present between covalent molecules.15•Covalent compounds are composed of discrete molecules. •The nature of the forces between molecules depends on the functional group present. There are three different types of interactions, shown below in order of increasing strength:van der Waals forcesdipole-dipole interactionshydrogen bonding16van der Waals Forces•van der Waals forces are also known as London forces.•They are weak interactions caused by momentary changes in electron density in a molecule.•They are the only attractive forces present in nonpolar compounds.Even though CH4 has no net dipole, at any one instant its electron density may not be completely symmetrical, resulting in a temporary dipole. This can induce a temporary dipole in another molecule. The weak interaction of these temporary dipoles constitutes van der Waals forces.17•All compounds exhibit van der Waals forces.•The surface area of a molecule determines the strength of the van der Waals interactions between molecules. The larger the surface area, the larger the attractive force between two molecules, and the stronger the intermolecular forces.Figure 3.1Surface area andvan der Waals forces18•van der Waals forces are also affected by polarizability.•Polarizability is a measure of how the electron cloud around an atom responds to changes in its electronic environment.Larger atoms, like iodine, which have more loosely held valence electrons, are more polarizable than smaller atoms like fluorine, which have more tightly held electrons. Thus, two F2 molecules have little attractive force between them since the electrons are tightly held and temporary dipoles are difficult to induce.19Dipole-Dipole Interactions•Dipole—dipole interactions are the attractive forces between the permanent dipoles of two polar molecules.•Consider acetone (below). The dipoles in adjacent molecules align so that the partial positive and partial negative charges are in close proximity. These attractive forces caused by permanent dipoles are much stronger than weak van der Waals forces.20•Hydrogen bonding typically occurs when a hydrogen atom bonded to O, N, or F, is electrostatically attracted to a lone pair of electrons on an O, N, or F atom in another molecule.Hydrogen Bonding21Note: as the
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