Lecture Notes: Redox Reactions and Organic Chemistry

Redox Reactions

Oxidation

• Loss of electrons
• More positive oxidation numbers
• Reducing agents

Reduction

• Gain of electrons
• More negative oxidation numbers
• Oxidizing agents

Principles

• Sum of oxidation charges in a molecule must equal zero unless otherwise specified.

Hydrogen's Role

• Can act as both an oxidant and reductant.

Characteristics of Reductants and Oxidants

• Reductants:
  • Often metals with half-filled valence electrons
  • Low electronegativity
  • Donate electrons to oxidants (e.g., metals oxidize to form ions)
• Oxidants:
  • Often non-metals with high electronegativity
  • Accept electrons to fill valence shell
  • Form negatively charged ions

Identifying Redox Reactions

• Example: Zn + HCl → ZnCl₂ + H₂ shows changes in Zn and H oxidation states.
• If oxidation numbers do not change, the reaction is not a redox reaction.

Redox Half Reactions

• Demonstrates complementary processes:
  • Example: Mg + Br₂ → MgBr₂
    • Mg → Mg²⁺ + 2e⁻ (oxidation)
    • Br₂ + 2e⁻ → 2Br⁻ (reduction)

Balancing Redox Reactions

• Under acidic conditions: Add H⁺ to balance oxygen.
• Balance charges and elements by adding electrons to appropriate sides.

Corrosion

• A form of redox reaction where metals revert to their oxidized state, e.g., rusting of iron.

Organic Chemistry

Introduction

• Study of carbon-containing compounds
• Organic molecules are synthesized in labs and occur naturally.

Carbon Bonding

• Carbon forms covalent bonds with four other atoms (diversity of structures)
• Stability due to strong C-C bonding

VSEPR Theory

• Methane (CH₄) represents trigonal pyramidal shape.

Naming Conventions

• Based on carbon atom count and type of bonds (single, double, triple).
• Saturated molecules: all possible hydrogens bonded to carbon.

Isomers

• Same formula, different structures.

Functional Groups

• Groups attached to carbon skeleton influencing reactivity and properties.
• Naming involves identifying functional groups and their positions.

Alkanes, Alkenes, Alkynes

• Alkanes: Single bonds, saturated
• Alkenes: Contain double bonds
• Alkynes: Contain triple bonds

Nomenclature

• Alkanes named by longest carbon chain and substituents.
• Use prefixes (meth-, eth-, etc.) and suffixes (-ane, -ene, -yne).

Halogens

• Treated as substituents in naming (e.g., bromo, fluoro, chloro, iodo).

These notes provide a summarized overview of redox reactions and foundational concepts in organic chemistry, including nomenclature and structural considerations.