Water
- Created by: Lois Maxwell
- Created on: 25-02-14 15:05
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- Water
- Hydrogen Bonding
- 2 hydrogen atoms are covalently bonded to 1 oxygen atom
- Hydrogen has a slight +ive charge and oxygen has a slight -ive charge - polar molecule
- Water molecules form hydrogen bonds with each other
- Ice - decrease in temperature = less kinetic energy: hydrogen bonds don't break as easily; less dense so it floats
- Cohesion = the attraction of water molecules due to hydrogen bonding
- Surface tension = the 'skin' on the surface of water formed as a result of hydrogen bonds pulling the surface molecules downwards
- Properties of water
- Solvent
- Metabolic processes in all organisms rely on chemicals being able to react together in solution
- Any molecule that is polar will dissolve in water
- Water molecules cluster around the charged parts of the solute and keeps the solute molecules apart so they are dissolved
- Liquid
- Acts as an ideal liquid transport medium for multicellular organisms
- Cohesion
- Water molecules stick to each other creating surface tension
- Makes long, thin water columns very strong and difficult to break
- Freezing
- Forms ice on the surface - water underneath becomes insulated and less likely to freeze
- Thermal stability
- Large bodies of water have fairly constant temperatures
- Evaporation of water can cool surfaces by removing heat
- Metabolic
- Water takes part as a reactant in some chemical processes, e.g. in hydrolysis
- Solvent
- Condensation and hydrolysis
- Condensation = monomers are joined together by covalent bonds to produce a polymer, and a water molecule is released
- Hydrolysis = a polymer is broken down into monomers by the breaking of covalent bonds and the addition of a water molecule
- Hydrogen Bonding
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