Water

• What are polar molecules?


  Molecules with a partial positive and partial negative charge due to an uneven distribution of a pair of electrons within a covalent bond.

  
• What are non-polar molecules?

  Molecules which have no partial charges due to an even distribution of a pair of electrons within a covalent bond.
• Which symbol represents polar charges?

   δ+ and  δ−
• What is the intermolecular force between water molecules called?

  A hydrogen bond (it isn’t a bond but rather an electrostatic attraction)

  
• How does a hydrogen bond form?

  when a hydrogen in a water molecule  δ+ is electrostatically attracted to oxygen in an adjacent water molecule  δ−
• Why can water be described as dipolar?

  As it has both a partial positive and partial negative charge.
• What are the five key properties of water?

  1. Metabolite
  2. Solvent
  3. High Heat Capacity
  4. Large Latent Heat of Vaporisation
  5. Strong cohesion between water molecules
• What is a metabolite and why is it important to organism?

  • A substance formed or used in a metabolic reaction
  • Used in hydrolysis or condensation reactions
• How is water used as a solvent and why is that important to organisms?

  • Water is dipolar so it can dissolve both negative and positive charges
  • Water can be used as a transport medium (blood)
  • Allows chemical reactions to occur

  
• Why has water got a high specific heat capacity and why is that advantageous to organisms?

  • As lots of energy is required to break hydrogen bonds
  • Means that if surrounding temperature changes, optimal temperature can be maintained -> enzymes
  • Allows water to be a suitable habitat
• Why has water got a high latent heat of vaporisation and why is that advantageous to organisms?

  • Due to hydrogen bonds
  • Provides a cooling effect for organisms (sweat)
• Why has water got a strong cohesion and why is this advantageous to organisms?

  • Water molecules stick together due to hydrogen bonds (cohesion)
  • Water molecules stick to other thongs (adhesion)
  • Cohesion allows a continuous column of water to move up the xylem due to transpiration
  • Also provides water tension, allowing small invertebrates to live on water

  
• what does hydrophobic mean?

  substances that repel water and do not dissolve in water like polar molecules
• What does hydrophilic mean?


  Molecules which are attracted to water and dissolve in it