Organic Chemistry

Organic Nomenclature

Organic nomenclature is the systematic method for naming organic compounds based on their structure. Understanding nomenclature allows chemists to communicate molecular structures unambiguously.

• Alkanes: Saturated hydrocarbons with only single bonds. Named with the suffix -ane (e.g., methane, ethane).

• Alkenes: Unsaturated hydrocarbons with at least one double bond. Named with the suffix -ene (e.g., ethene).

• Alkynes: Unsaturated hydrocarbons with at least one triple bond. Named with the suffix -yne (e.g., ethyne).

• Aromatic compounds: Contain benzene rings; named based on the parent aromatic system (e.g., toluene, phenol).

• Aliphatic compounds: Non-aromatic hydrocarbons, including alkanes, alkenes, and alkynes.

Example: The formula C2H6 is named ethane.

Functional Groups

Functional groups are specific groups of atoms within molecules that determine the chemical properties of those molecules.

• Alcohol: Contains an -OH group (e.g., ethanol).

• Carbonyl: Contains a C=O group; found in aldehydes and ketones.

• Aldehyde: Carbonyl group at the end of a chain (e.g., formaldehyde).

• Ketone: Carbonyl group within a chain (e.g., acetone).

• Carboxylic acid: Contains -COOH group (e.g., acetic acid).

• Ether: Contains an oxygen atom between two alkyl groups (e.g., diethyl ether).

• Ester: Contains -COO- group (e.g., ethyl acetate).

• Anhydride: Derived from two carboxylic acids (e.g., acetic anhydride).

• Other groups: Alkyl (methyl, ethyl, propyl), halides (chloro, fluoro, bromo, iodo), amine, amide, nitrile.

Example: CH3CH2OH is an alcohol (ethanol).

Isomerism in Organic Compounds

Isomers are compounds with the same molecular formula but different structures or spatial arrangements.

• Structural isomers: Differ in the connectivity of atoms.

• Geometric isomers: Differ in spatial arrangement due to restricted rotation (e.g., cis/trans in alkenes).

• Optical isomers: Non-superimposable mirror images (chiral molecules).

Example: Butane and isobutane are structural isomers.

Types of Organic Reactions

Organic compounds undergo various types of reactions, each characterized by the changes in functional groups or molecular structure.

• Condensation: Two molecules combine, often releasing a small molecule (e.g., water).

• Dehydration: Removal of water from a molecule.

• Oxidation/Reduction (REDOX): Transfer of electrons; oxidation increases oxygen or decreases hydrogen, reduction is the opposite.

• Addition: Atoms added to a double or triple bond.

• Displacement: One atom or group replaces another.

• Elimination: Removal of atoms/groups, often forming double bonds.

• Substitution: Replacement of one atom/group with another.

Example: Hydration of ethene (addition reaction) forms ethanol.

Nuclear Chemistry

Nucleons, Nuclides, and Notation

Nuclear chemistry studies the structure and reactions of atomic nuclei. Key terms include:

• Nucleons: Protons and neutrons in the nucleus.

• Nuclide: A specific isotope of an element, defined by its number of protons and neutrons.

• Expanded notation: AZX, where A = mass number, Z = atomic number, X = element symbol.

Example: 146C represents carbon-14.

Types of Nuclear Decay and Particles

Nuclear decay is the process by which unstable nuclei lose energy by emitting radiation.

• Alpha (α) decay: Emission of an alpha particle (He nucleus).

• Beta (β-) decay: Emission of an electron.

• Beta (β+) decay (positron emission): Emission of a positron.

• Gamma (γ) emission: Emission of high-energy photons.

• Electron capture: Nucleus captures an inner electron.

Example: 146C → 147N + β-

N/Z Ratio, Band of Stability, and Magic Numbers

The neutron-to-proton (N/Z) ratio determines nuclear stability. The band of stability is the region where stable nuclides are found. Magic numbers are specific numbers of nucleons that confer extra stability.

• N/Z ratio: Stable nuclei have specific neutron/proton ratios.

• Band of Stability: Plot of stable nuclides on a graph of N vs Z.

• Magic Numbers: 2, 8, 20, 28, 50, 82, 126 (numbers of protons or neutrons that are especially stable).

Example: Predicting decay: Nuclides above the band of stability undergo β- decay; below, β+ decay or electron capture.

Nuclear Decay Kinetics

Nuclear decay follows first-order kinetics, meaning the rate depends on the number of undecayed nuclei.

• First-order decay equation:

• Decay constant (k): Characterizes the rate of decay.

• Half-life (T1/2): Time for half the nuclei to decay.

Example: If k = 0.001 s-1, then T1/2 = 693 s.

Nuclear Reaction Equations

Nuclear reactions must conserve mass number and atomic number. Equations are written to show reactants and products, ensuring both numbers add up.

• Writing equations: Identify missing species by balancing mass and atomic numbers.

Example:

Energy Units: eV, MeV, and Joules

Energy in nuclear chemistry is often measured in electron volts (eV), mega electron volts (MeV), and joules (J).

• 1 eV: Energy gained by an electron moving through 1 volt;

• 1 MeV:

• Conversion: To convert MeV to J, multiply by

Example: 2 MeV = J

Summary Table: Types of Nuclear Decay

Additional info: Academic context and examples were added to clarify and expand on brief points from the original study guide.