2 STRUCTURE OF WATER MOLECULE Hydrogen atomHydrogen atomFormula:H2OOxygen atom
3 H+ H+ O- 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 of electrons between atoms Sharing electronsSharing of electrons between atomsOxygen has 6 valence electronsHydrogen has 1 valence electronHHO
5 Cohesion Water molecules stick to each other. Creates surface tension Positive side attracted to negative sideCreates surface tensionWater 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 Floats on water Ice = g/mlWater = g/mlFloats on waterLakes and ponds freeze from top to bottomInsulates ponds from freezing solidProtects organisms in ponds and lakesArrangement 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 HeatIt 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 lossThis helps to maintain constant temperature of oceans and body temperature.Substance Specific Heat (cal/g-C) Water 1.00 Aluminum 0.215 Iron 0.108Gold 0.031 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 chargesWater 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 of H+ and OH- ions.pH measures the concentration of H+ ions.pH scaleACIDS NEUTRAL BASES(Strongest) (Weakest) (Weakest) (Strongest)