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Water’s life supporting properties
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Water’s life supporting properties

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  • 1. Water’s Life-Supporting Properties
  • 2. The structure of Water The end with the two hydrogen atoms is slightly positive. Oxygen end of the molecule has a slight negative charge POLAR MOLECULE!!
  • 3. The electromagnetic attractive interaction between polar molecules, in which hydrogen (H) is bound to a highly electronegative atom, such as nitrogen (N), oxygen (O) or fluorine (F). Hydrogen bond is not a true bond but a strong dipole- dipole attraction, and should not be confused with a covalent bond
  • 4. Q:How can water molecules be compared to magnets? A:Both water molecules and magnets have opposite poles that cause them to be attracted to each other in a specific orientation.
  • 5. Life-Supporting Properties of WATER WATER H2O Cohesion & Adhesion Related to high surface tension Temperature Moderation (High heat capacity) Dissolve Substances (Universal solvent) Low density of ice (changes in density) The polar nature of water and the effects of hydrogen bonding explain most of water´s unique properties
  • 6. Life-Supporting Properties of WATER Cohesion & Adhesion Related to high surface tension COHESION: property of like molecules (of the same substance) to stick to each other due to mutual attraction with HB. ADHESION: property of different molecules or surfaces to cling to each other thanks to HB Surface tension:Molecules are pulled equally in all directions by neighboring molecules Capillary Action: When a liquid flows through a narrow space
  • 7. Life-Supporting Properties of WATER COHESION + ADHESION Surface tension: Result of cohesive forces between adjacent molecules Molecules are pulled equally… Capillary Action: the result of cohesive and adhesive forces… When a liquid flows through a narrow space
  • 8. Life-Supporting Properties of WATER Temperature Moderation (High heat capacity) TEMPERATURE measure of the average energy of random motion of the particles in a substance. When two substances differ in temperature, thermal energy in the form of heat is transferred from the warmer substance to the cooler one water heats up much more slowly than metal→ because of hydrogen bonding, water has a better ability to resist temperature change than most other substances THERMAL ENERGY total amount of energy associated with the random movement of atoms and molecules in a sample of matter
  • 9. Life-Supporting Properties of WATER Temperature Moderation (High heat capacity) THERMAL ENERGY total amount of energy associated with the random movement of atoms and molecules in a sample of matter TEMPERATURE measure of the average energy of random motion of the particles in a substance. . HB RELATION: Some thermal energy breaks hydrogen bonds → water absorbs the same amount of thermal energy but undergoes less temperature change than the metal As water cools, it forms hydrogen bonds → releases thermal energy in the form of heat, so there is less of a drop in temperature than in metal
  • 10. Life-Supporting Properties of WATER Dissolve Substances (Universal solvent) SOLUTION Uniform mixture of two or more substances SOLVENT The substance that dissolves the other substance and is present in the greater amount SOLUTE The substance that is dissolved and is present in a lesser amount HB RELATION: areas of slight electric charge attract the polar ends of water molecules. Water molecules cling to these charged regions and separate the sugar molecules from one another EXAMPLE Sodium chloride dissolves as Na+ and Cl-ions become attracted to water molecules and break away from the surface of the solid
  • 11. Life-Supporting Properties of WATER Low density of ice (changes in density)DENSITY: amount of matter in a given volume. In most substances the solid state is more dense than the liquid. Water is just the opposite—its solid form (ice) is less dense than the cold liquid form Ice floats because its molecules are less densely packed than those in liquid water. HB RELATION: Because the molecules in liquid water are moving faster than those in ice, there are fewer and more short-lived hydrogen bonds between molecules. The liquid water molecules can fit more closely
  • 12. Video water’s life-supporting properties • http://www.youtube.com/watch?v=aVmU3CL xvgU 4 MIN • http://www.youtube.com/watch?v=HVT3Y3_g HGg 11 MIN

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