Organic Chemistry Lecture Notes

Introduction to Organic Chemistry

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

Bonding Preferences by Element

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

Lewis Structures

• Essential for visualizing molecular structure.
• Water (H2O): Oxygen forms 2 bonds; hydrogen forms 1. Oxygen has two lone pairs.
• Methyl Fluoride (CH3F): Carbon forms 4 bonds; hydrogen and fluorine form 1 bond each. Fluorine has three lone pairs.

Types of Covalent Bonds

• Polar Covalent Bonds: Unequal sharing of electrons (e.g., C-F bond in methyl fluoride).
• Non-polar Covalent Bonds: Equal sharing of electrons (e.g., C-H bonds in methane).
• Hydrogen Bonds: Special type of polar covalent bond involving hydrogen with N, O, or F.

Ionic Bonds

• Formation: Transfer, not sharing, of electrons (e.g., NaCl formation).
• Characteristics: Attraction between positively and negatively charged ions (cations and anions).

Alkanes, Alkenes, and Alkynes

• Alkanes: Saturated hydrocarbons (e.g., methane, ethane).
• Alkenes: Unsaturated hydrocarbons with at least one double bond (e.g., ethene).
• Alkynes: Unsaturated hydrocarbons with at least one triple bond (e.g., ethyne).

Bond Length and Strength

• Single Bonds: Longest (e.g., C-C 154 pm)
• Double Bonds: Intermediate length
• Triple Bonds: Shortest and strongest

Sigma and Pi Bonds

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

Hybridization

• Determination: Sum of atoms and lone pairs around a carbon atom.
  • sp3: 4 groups
  • sp2: 3 groups
  • sp: 2 groups

Formal Charges

• Calculation: Valence electrons - (bonds + dots)
• Examples include carbocations and carbanions.

Functional Groups and Nomenclature

• Alcohols (e.g., Ethanol): Contain OH group.
• Aldehydes: Carbonyl group at the end (e.g., Ethanal).
• Ketones: Carbonyl group in the middle (e.g., Propanone).
• Ethers: Oxygen between two carbons (e.g., Dimethyl ether).
• Carboxylic Acids: COOH group (e.g., Pentanoic Acid).
• Esters: Formed from acids and alcohols (e.g., Methyl Ethanoate).

Structure Expansion

• Methyl groups (CH3) are at the ends; methylene (CH2) and methine (CH) groups appear centrally.

Additional Resources

• For specific topics, refer to online playlists and resources for detailed explanations and examples.