Organic Chemistry Lecture Notes

Introduction to Organic Chemistry

• Focuses on organic compounds containing carbon atoms.
• Carbon forms four bonds.

Bonds Formed by Various Elements

• Hydrogen: 1 bond
• Beryllium: 2 bonds
• Boron: 3 bonds
• Carbon: 4 bonds
• Nitrogen: 3 bonds
• Oxygen: 2 bonds
• Halogens (e.g., Fluorine, Chlorine, Bromine, Iodine): 1 bond (occasionally 7)

Lewis Structures

• Lewis structures help visualize molecule structures.
• Example: Water (H2O) uses two bonds for oxygen and one for hydrogen.
• Lone pairs are added to satisfy the octet rule.

Types of Bonds

• Covalent Bonds: Electrons are shared.
  • Polar Covalent Bonds: Unequal sharing due to electronegativity differences (e.g., C-F bond in methyl fluoride).
  • Nonpolar Covalent Bonds: Equal sharing (e.g., C-H bond).
  • Hydrogen Bonds: Special type of polar covalent bond.
• Ionic Bonds: Electrons are transferred (e.g., Na-Cl).

Alkanes and Alkyl Groups

• Saturated hydrocarbons: Methane, Ethane, Propane, Butane, etc.
• General formula: C_nH_{2n+2}_

Alkenes and Alkynes

• Alkenes: At least one double bond (e.g., Ethene).
• Alkynes: At least one triple bond (e.g., Ethyne).

Bond Length and Strength

• Single bonds are longer than double bonds, which are longer than triple bonds.
• Triple bonds are the strongest; single bonds are the weakest.

Sigma and Pi Bonds

• Single bond: 1 sigma bond.
• Double bond: 1 sigma + 1 pi bond.
• Triple bond: 1 sigma + 2 pi bonds.
• Sigma bonds are stronger than pi bonds.

Hybridization

• sp3: Attached to 4 groups.
• sp2: Attached to 3 groups.
• sp: Attached to 2 groups.
• Bond hybridization (e.g., CH bond): Determined by the atoms' hybridization (e.g., sp3-s).

Formal Charge Calculation

• Formula: Valence electrons - (bonds + dots).
• Examples with sulfur and nitrogen discussed.

Functional Groups

• Alcohols: Contain an OH group.
• Aldehydes: Contain a carbonyl group at the end.
• Ketones: Carbonyl group in the middle.
• Ethers: Oxygen between two carbons.
• Esters: Carbonyl and alkoxy group.
• Carboxylic Acids: Carbonyl and hydroxyl group.

Practice with Molecular Structures

• How to expand condensed structures.
• Distinguishing functional groups and their locations in molecules.

Resources

• Organic chemistry playlists and additional resources for further study are available online.