Lecture Notes on Chemical Bonds and Reactions

Types of Chemical Bonds

• Covalent Bonds: Strongest type of chemical bond.
• Ionic Bonds: Weaker than covalent bonds; dissolve easily in water.
• Hydrogen Bonds: Weakest type of chemical bond.

Chemical Reactions

• Chemical reactions involve breaking, forming, and rearranging bonds.
• Similar to cooking: follow a specific order to achieve desired results.
• Cellular Respiration: Common chemical reaction that occurs in cells; requires oxygen and produces ATP.
  • Anaerobic produces less ATP than aerobic.
  • Oxygen is crucial for higher ATP yield.

Enzymes and Their Role

• Enzymes are specialized proteins that act as biological catalysts.
• Speed up chemical reactions in the body, sometimes by trillions of times.
• Highly sensitive to temperature, pH, and radiation.
• Important for maintaining proper sequence and order of reactions.

Types of Chemical Reactions

• Synthesis (Anabolic) Reactions: Combine smaller molecules into larger ones; energy is required.
  • Example: Dehydration synthesis removes water to bond molecules.
• Decomposition (Catabolic) Reactions: Break down larger molecules into smaller ones; energy is released.
  • Example: Hydrolysis adds water to break down molecules.
• Reversible Reactions: Can proceed in both directions.
• Exchange Reactions: Atoms exchange partners; similar to swapping.

Electrolytes and Their Importance

• Electrolytes dissolve in water to produce ions; crucial for conducting electricity in the body.
• Sodium (Na⁺) and Chlorine (Cl⁻) are common examples.
• Cations: Positively charged ions.
• Anions: Negatively charged ions.

pH Scale

• Measures the concentration of hydrogen ions in a solution.
• Acidic: pH less than 7; releases hydrogen ions.
• Basic: pH greater than 7; releases hydroxyl ions.
• Neutral: pH of 7 (e.g., pure water).
• Logarithmic scale: each unit change represents a ten-fold difference in ion concentration.

Examples of pH in Everyday Substances

• Stomach acid: pH around 1-3
• Lemon juice: pH around 2
• Vinegar: pH around 3
• Milk: pH around 6
• Pure water: pH of 7
• Household bleach: pH around 9.5

Importance of Homeostasis and pH Balance

• Homeostasis: Maintaining a stable internal environment.
• Different body parts have specific pH ranges:
  • Blood: 7.35-7.45
  • Stomach: 0.9-3
  • Small intestine: 7.4-7.8
  • Urine: 5-8
• Acidosis: Blood pH below 7.35
• Alkalosis: Blood pH above 7.45
• Buffers help resist changes in pH to maintain homeostasis.