Families of Carbon Compounds, Functional Groups, and Intermolecular Forces
Terms for Chapter 2: Families of Carbon Compounds, Functional Groups and Intermolecular Forces
Hydrocarbon (Sec 2.1)
Molecule that contains only carbon and hydrogen atoms.
Saturated Compound (Sec 2.1, 7.13)
A compound that contains only single covalent bonds, and has the maximum number of hydrogen atoms that are possible.
Unsaturated Compound (Sec 2.1, 7.13)
A compound that contains multiple covalent bonds, has fewer than the maximum number of hydrogen atoms, and is capable of reacting with hydrogen under the proper conditions.
Alkane (Sec 2.1A, 4.1, 4.2, 4.3, 4.7, 4.16)
Saturated hydrocarbon that contains only single covalent bonds; it has the general molecular formula CnH2n+2.
Alkene (Sec 2.1B, 2.4A, 4.1)
Unsaturated hydrocarbon that contains at least one C=C double covalent bond; its molecular formula loses two hydrogen atoms for every double bond, as compared to the corresponding alkane. Also called an olefin.
Alkyne (Sec 2.1C, 4.1)
Unsaturated hydrocarbon that contains at least one C≡C triple covalent bond; its molecular formula loses four hydrogen atoms for every triple bond, as compared to the corresponding alkane.
Aromatic Hydrocarbon (Sec 2.1D, 14.1 to 14.11, Lab 15)
A planar cyclic conjugated system, with alternating single and double bonds in the ring, that is stabilized by electron delocalization.
Benzene (Sec 2.1D, 14.1 – 14.6)
An aromatic six-carbon ring with the molecular formula C6H6; each carbon atom is sp2 hybridized with one p orbital that contains one electron.
Kekule Structure (Sec 2.1D, 14.4)
Structure in which lines are used to represent bonds, such as the structure of benzene, which is drawn as a hexagon of carbon atoms with alternating single and double bonds around the ring, and with one hydrogen atom attached to each carbon.
Polar Covalent Bond (Sec 2.2)
A covalent bond in which the electrons are not equally shared because of differing electronegativities of the bonded atoms.
Heteroatom (Sec 2.2)
An atom in an organic compound that forms covalent bonds, and is neither carbon nor hydrogen.
Electronegativity (Sec 1.4A, 2.2)
A measure of the ability of an atom to attract shared electrons to itself, and thereby polarize that covalent bond.
Dipole Moment (μ) (Sec 2.2)
A measure of the degree of charge separation in a molecule, which is the product of the positive charge, Q, in electrostatic units (esu) and the distance, d, that separates them, in centimeters: μ = Q ∙ d, with units in debyes, D, where 1 D = 1 x 10–18 esu ∙ cm = 3.336 x 10–30 C ∙ m (coulomb meter). The larger the dipole moment, the more polar the molecule.
Dielectric Constant (ε or κ) (Sec 6.13D, Lab 3.2)
- The increase in capacitance, equal to ε, that is created when a substance fills the space between the plates of a capacitor.
- A measure of the polarity of a molecule, and the ability to insulate opposite charges from each other; a vacuum has ε = 1; molecules with 1 < ε < 3 are nonpolar; molecules with 3 ≤ ε < 10 are slightly polar; molecules with 10 ≤ ε < 20 are moderately polar; molecules with ε ≥ 20 are very polar.
Electrostatic Potential Map (Sec 1.8, 2.2A, 3.4)
Computer generated structure that uses color to show the relative distribution of electron density at the Van der Waals surface of a molecule or ion; violet shows electron-poor regions that have a positive charge (+); blue to blue-green show regions that have a partial positive charge (δ+); green shows regions of normal electron density with no charge (0); yellow to orange show regions that have a partial negative charge (δ─); red shows electron-rich regions that have a negative charge (─). Also called map of electrostatic potential.
Van der Waals Surface (Sec 1.12, 2.2A)
A plot of the furthest extent of a molecule’s electron cloud, and thus its overall shape; when the van der Waals surface is penetrated by another molecule, it experiences strong repulsive forces between the overlapping electron clouds.
Polar Molecule (Sec 2.3)
A molecule with a dipole moment.
Functional Group (Sec 2.4)
The particular group of atoms in a molecule that primarily determines how the molecule reacts.
Alkyl Group (Sec 2.4A)
Group obtained by removing a hydrogen atom from an alkane; abbreviated R.
Methyl Group (Sec 2.4A)
The CH3– group; obtained by removing one hydrogen atom from methane, CH4.
Methylene Group (Sec 2.4B)
The -CH2– group; obtained by removing two hydrogen atoms from methane, CH4.
Methine Group
The >CH- group; obtained by removing three hydrogen atoms from methane.
Aryl Group (Sec 6.1, 15.1)
The general name for a group obtained by the removal of a hydrogen from a ring position of an aromatic hydrocarbon, abbreviated Ar-.
Phenyl Group (Sec 2.4B, 6.1, 14.2)
The C6H5– group; obtained by removing a hydrogen atom from benzene, C6H6. Abbreviated Ph– or φ–.
Benzyl Group (Sec 2.4B, 14.2)
The C6H5CH2– group; obtained by removing a hydrogen atom from the methyl group of toluene, C6H5CH3. Abbreviated Bn–.
Primary Carbon (Sec 2.5)
Carbon atom that has only one other carbon atom attached to it
Secondary Carbon (Sec 2.5)
Carbon atom that has two other carbon atoms attached to it.
Tertiary Carbon (Sec 2.5)
Carbon atom that has three other carbon atoms attached to it.
Haloalkane (Sec 2.5, 6.1)
Compound in which a halogen atom (F, Cl, Br, I) replaces a hydrogen atom of an alkane, with the general formula RX. Also called alkyl halide.
Alcohol (Sec 2.6, 4.3F, 11.1)
Molecule containing a hydroxyl group, –OH, bound to a sp3 hybridized carbon atom, with the general formula ROH.
Ether (Sec 2.7, 11.1)
Molecule containing an oxygen atom bonded to two alkyl or aryl groups, with the general formula ROR’.
Amine (Sec 2.8, 20.1)
A molecule containing an amino group, -NH2, -NHR, or -NR2, obtained by removing one or more hydrogen atoms from ammonia, with the general formula RNH2, RNHR, or RNR2. A primary amine has one R group attached to the N atom, a secondary amine has two R groups attached to the N atom, and a tertiary amine has three R groups attached to the N atom.
Carbonyl Group (Sec 2.9, 12.1, 16.1)
A functional group consisting of a carbon atom doubly bonded to an oxygen atom, >C=O.
Aldehyde (Sec 2.9, 12.1, 16.1)
A molecule containing a terminal carbonyl group, >C=O, that is attached to one hydrogen and one other carbon atom, with the general formula RCHO.
Ketone (Sec 2.9, 12.1, 16.1)
A molecule containing an internal carbonyl group, >C=O, that is attached to two other carbon atoms, with the general formula RCOR.
Carboxylic Acid (Sec 2.10A, 17.2A)
Molecule containing a carbonyl group, >C=O, that is attached to a hydroxyl group, –OH, which is called a carboxyl group, –COOH, with the general formula RCOOH.
Ester (Sec 2.10B, 17.2E)
Molecule containing a carbonyl group, >C=O, that is attached to an alcohol group, –OR’, with the general formula RCOOR’.
Amide (Sec 2.10C, 17.2H)
Molecule containing a carbonyl group, >C=O, that is attached to an amino group, –NR2, with the general formula RCONR’2 (R may be hydrogen).
Nitrile (Sec 2.11, 17.2I)
Molecule containing a cyano group, –C≡N, with the general formula RCN.
Physical Properties (Sec 2.13)
Properties of a substance that can be measured without changing its chemical composition, such as melting point, boiling point, density, refractive index, and solubility in common solvents.
Melting Point (Sec 2.13A, Lab 3.3)
The temperature at which an equilibrium exists between the well ordered crystalline state and the more random liquid state, and which the solid has the same vapor pressure as the liquid in equilibrium with it.
Intermolecular Forces (Sec 2.13, 2.14)
All of the noncovalent electrostatic forces of attraction or repulsion which act between neighboring molecules, groups and atoms, which include the forces of ions, dipoles and electron clouds; these forces determine many physical properties of the molecules, such as melting point, boiling point and solubility. In biochemistry, intermolecular forces also include the ionic forces of molecular ions, such as proteins, nucleic acids, phospholipids, etc.
Coulomb’s Law
The force, F, exerted by one charged object on another is proportional to the product of the charges, Q, in coulombs, and inversely proportional to the square of the distance, d, that separates them, in meters: F = k ∙ Q1 ∙ Q2 / d2, where Coulomb’s constant, k = 8.9875 x 109 N ∙ m2 / C2.
Ion-Ion Forces (Sec 2.13A)
Very strong electrostatic forces between oppositely charged ions. Also called cation-anion forces.
Dipole-Dipole Forces (Sec 2.13B)
Weak forces between molecules that have permanent dipole moments, due to attraction of the charged end of one dipole to the oppositely charged end of an adjacent dipole; often allows solvation of polar molecules in a polar solvent.
Hydrogen Bond (Sec 2.13B)
The strongest type of dipole-dipole force, which occurs between an O, N, or F atom, and a H atom that is bound to another O, N, or F atom; it often allows solvation of molecules in water.
Polarizability (Sec 2.13B, 6.13C)
The susceptibility of the electron cloud of an uncharged atom to distortion by the influence of an electric charge; larger atoms have greater polarizability than smaller atoms.
London Dispersion Forces (Sec 2.13B)
Weak attractive forces between induced dipoles that exist between all molecules, that are produced when a temporary unsymmetrical electron distribution produces a temporary polarity in an atom, which induces a temporary polarity of opposite charge in an adjacent atom. The strength of London dispersion force increases with increasing polarizability of the atoms and increasing surface area of the molecule. Also called London forces, or dispersion forces.
Dipole-Induced Dipole Forces (Sec 2.13)
Weak attractive forces between a polar molecule and a nonpolar molecule, which are produced when the charged end of the permanent dipole induces a temporary polarity of opposite charge in the nonpolar molecule.
Van der Waals Forces (Sec 2.13B, 4.7)
All of the intermolecular forces that do not involve cations, anions or covalent bonds, such as the forces of permanent dipoles, hydrogen bonds, induced dipoles, and electron clouds.
Boiling Point (Sec 2.13C, 2.13C, Lab 4.2)
The temperature of a liquid at which the equilibrium vapor pressure equals the total external pressure, and which the rate of evaporation increases dramatically with bubbles forming in the liquid.
Ion-Dipole Forces (Sec 2.13D)
Moderate strength electrostatic forces between an ion and the oppositely charged end of a permanent dipole; often allows solvation of ions in a polar solvent.
Solubility (Sec 2.13D)
The amount of solute that can dissolve in a solvent at a given temperature; the like-dissolves-like rule states that polar molecules dissolve in polar solvents, and nonpolar molecules dissolve in nonpolar solvents.
Hydrophilic Group (Sec 2.13D, Lab 5.3)
A polar (water-loving) group that seeks an aqueous environment.
Hydrophobic Group (Sec 2.13D, Lab 5.3)
A nonpolar (water-fearing) group that avoids an aqueous surrounding and seeks a nonpolar environment. Also called lipophilic group.
Hydrophobic Effect (Sec 2.13D, Lab 5.3)
The excluding of nonpolar molecules from an aqueous solution.
Water Solubility (Sec 2.13E, Lab 25.3B)
An organic compound is water soluble if at least 3 g of the compound dissolves in 100 mL of water, or at least 30 mg dissolves in 1 mL of water (3% m/V).
Infrared Spectroscopy (Sec 2.15, Lab 8.2)
A type of optical spectroscopy that measures the absorption of infrared radiation ( 4000 – 400 cm-1, or 2.5 – 25 μm ), and it provides structural information about functional groups present in the compound being analyzed. Also called IR spectroscopy.