Chemistry of Water

Importance of Water

• Inorganic molecule
• Most important compound in the body
• 50%+ of a normal adult's body weight

Molecular Structure

• Composed of 1 Oxygen atom and 2 Hydrogen atoms
• Atoms bonded covalently
  • Covalent bonds: Sharing of electron pairs between atoms

Polarity of Water

• Polar molecule
• Unequal sharing of electrons
  • Oxygen side: 2 partial negative charges
  • Hydrogen side: Slightly positive charges
• Can form up to 4 hydrogen bonds with adjacent water molecules

Hydrogen Bonds

• Result of unequal charge distribution (polarity)
• Allows water to act as an effective solvent

Solubility

• Hydrophilic substances: Dissolve or break apart in water ("water loving")
• Hydrophobic substances: Do not dissolve in water ("water fearing")

Examples

• Glucose: Dissolves and remains intact; forms hydration shell
• NaCl (Table Salt): Dissociates into Na+ and Cl- ions; forms hydration shell around each ion

Function as a Transporter

• Water-based fluids (e.g., blood) transport dissolved substances throughout the body
• Non-polar, hydrophobic substances (e.g., fats, cholesterol)
  • Require transport protein molecules to be transported in blood

Summary

• Water's molecular structure, polarity, and ability to form hydrogen bonds make it a unique and essential compound for various biological processes.