Chemistry Lecture Notes

Overview

• Topic: Biologically important bonds in living organisms
• Focus: Covalent and weak bonds like ionic and hydrogen bonds

Strong Chemical Bonds

• Covalent Bonds
  • Polar Covalent
  • Nonpolar Covalent
  • Link atoms to form molecules in cells

Weak Chemical Bonds

• Ionic Bonds

  • Weak in water
  • Example: Salt dissolving in water
  • Important ions: Sodium, Potassium, Calcium
  • Role in nerve conduction and muscle contraction

• Hydrogen Bonds

  • Important for 3D structure of proteins and DNA
  • Hold together nitrogenous bases in DNA
  • Involved in water molecule interactions

Water Molecule Bonding

• Polar Covalent Bonds

  • Between oxygen and hydrogen within a molecule

• Hydrogen Bonding

  • Occurs between water molecules
  • Partial positive charge on hydrogen attracts partial negative on oxygen
  • Weak electrical interaction (hydrogen bonds)
  • Water molecules can form up to four hydrogen bonds

Properties of Water

• Liquid State: Due to hydrogen bonding
• Surface Tension: Caused by hydrogen bonds
• Phases: Exists as solid, liquid, and gas

Chemical Reactions

• Formation of Water

  • Reaction: 2H₂ + O₂ → 2H₂O
  • Conservation of matter: Atoms rearrange, not created or destroyed

• Photosynthesis

  • Converts sunlight energy into chemical energy
  • Equation: Carbon dioxide + water → glucose + oxygen
  • Recognize glucose (C₆H₁₂O₆) structure

• Cellular Respiration

  • Equation: Oxygen + glucose → carbon dioxide + water + energy
  • Reverse of photosynthesis

Key Takeaways

• Conservation of Matter: Chemical reactions rearrange atoms, don't create/destroy
• Familiarity Required: Recognize glucose formula; understand reaction inversions

Conclusion

• Next Lecture: Properties of water
• Focus: Unique aspects and properties of water