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Understanding Water

Understanding Water. STRUCTURE OF WATER MOLECULE. Hydrogen atom. Hydrogen atom. Formula: H 2 O. Oxygen atom. POLARITY OF WATER. Different sides of molecule have different charges. Due to unequal sharing of electrons. H+ H+ O-

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Understanding Water

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  1. Understanding Water

  2. STRUCTURE OF WATER MOLECULE Hydrogen atom Hydrogen atom Formula: H2O Oxygen atom

  3. POLARITY OF WATER • Different sides of molecule have different charges. • Due to unequal sharing of electrons. H+ H+ O- • Oxygen side is negative because it has a stronger attraction of electrons.

  4. COVALENT BONDING Sharing electrons • Sharing of electrons between atoms • Oxygen has 6 valence electrons • Hydrogen has 1 valence electron H H O

  5. Cohesion • Water molecules stick to each other. • Positive side attracted to negative side • Creates surface tension • Water is pulled easily through small vessels (capillary action)

  6. Adhesion • Water molecules stick to other substances. • Water molecules can be pulled through other substances. Water molecules being attracted to side of a small glass tube. A meniscus is the dip in the water surface due to this attraction. Water molecules attracted to paper towel

  7. Low density of ice • Less dense than water • Ice = 0.9164 g/ml • Water = 0.9999 g/ml • Floats on water • Lakes and ponds freeze from top to bottom • Insulates ponds from freezing solid • Protects organisms in ponds and lakes Arrangement of ice provides s pace between molecules so it is lighter than water.

  8. High Heat of Vaporization • It takes a lot of energy for water to evaporate. • This prevents excessive loss of water from lakes and ponds in summer. High heat causing water to evaporate.

  9. High Specific Heat • It takes a lot of energy to change the temperature of water. • Water has the highest specific heat of all liquids except ammonia. • Heat energy used to break molecules is not available for increased kinetic energy for evaporation. It would take more energy for evaporation. • Larger numbers of water molecules per gram allows it to absorb more heat energy thus buffering against heat loss • This helps to maintain constant temperature of oceans and body temperature. Specific Heat for water: It takes 1 calorie of energy to raise 1 gram of water I degree Celsius

  10. Universal Solvent • Ionic and polar substances dissolve best in water. • Ionic and polar molecules have charges • Water is attracted to parts of other molecules causing them to separate. (see below) • Minerals and nutrients can be dissolved and transported more quickly and better throughout organisms. • Main solvent in organisms.

  11. Acids and Bases • Acids have excess H+ions. • Bases have excess OH- ions. • Neutral water has equal amounts ofH+ and OH- ions. • pH measures the concentration of H+ ions. pH scale ACIDS NEUTRAL BASES 1 2 3 4 5 6 7 8 9 10 11 12 13 14 (Strongest) (Weakest) (Weakest) (Strongest)

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