Emergent Properties of Water

Water is a Polar Molecule

  • Hydrogen is bonded through covalent bonds to oxygen atoms

  • Oxygen has a greater electronegativity than hydrogen

    S- and S+ signify where the molecule is more negative vs. more positive

  • Water molecules will create hydrogen bonds and organize at a high level of structural organization

Cohesion (like molecules sticking together) Vs. Adhesion (unlike molecules sticking together)

  • Allows for xylem sap (water and minerals) to move vertically, up against gravity in plants; phloem flows down (cohesion)

  • Allows for water to stay in the veins of plants even without tension (adhesion)

    Cohesion is shown between water molecules; Adhesion is shown between the walls of the plant and water molecules

High Surface Tension

  • Meaning that it takes greater force to shear or break the surface
  • This allows some organisms to live on the surface of the water

Moderation of Temperature

  • Water resists quick changes in temp. due to hydrogen bonding and high specific heat
    • High Specific Heat: the amount of kinetic energy it takes to change the temperature of 1 gram of a substance by 1 degree
  • Oceans act as heat reservoirs, moderating climates
  • This helps organisms maintain a homeostatic (internal steady state of conditions) body temperature
  • Allows for evaporative cooling; sweat
    • High Heat of Vaporization: the amount of heat it takes for liquid to vaporize

Temperature vs. Heat

  • Temp. is the average amount of kinetic energy independent of volume
  • Heat is the total amount of kinetic energy dependent of volume

Water Expands upon Freezing

  • Water is most dense at 4 degrees Celcius
  • Ice on top of water creates insulates the water below
  • When frozen molecules form a lattice-like structure

Versatile Solvent

  • Solvent: dissolving agent
  • Attracted to hydrophilic (water-liking) molecules, ionic compounds, and polar molecules
  • Not attracted to hydrophobic (water-fearing) molecules and non-polar molecules
  • Helps to transport substances in the solution phase