2.2 The Water Molecule  Polarity A water molecule is polar because there is an uneven distribution of electrons between the O and H atoms

Cohesion  Attraction between molecules of the same substance  Molecules on the surface of water are drawn inward (water beads)

Adhesion  Attraction between molecules of different substances  Ex: Water – Glass  Capillary action- water will rise in a narrow tube  Ex: roots of a plant

Solutions and Suspension  Mixture- material composed of 2 or more substances, physically mixed together  Salt & pepper, Earth’s atmosphere

Solutions  Components are evenly distributed  Solute -  Solvent -

Suspension  Mixture of water and non-dissolved material  Many biological fluids are solutions and suspensions (ex. Blood)

Acids, Bases, pH Water Hydrogen + Hydroxide ion ion

pH scale  Shows the concentration of H + ions in solution  0-14  Pure water = 7, neutral  <7=acidic, more H + ions than OH - ion  >7=_____________, more _______ than ___________.  Each step on scale represents a factor of 10

Acids  compound that forms _____ in solution  Higher concentrations of _____ ions than pure water  pH value = __________  Strong acids, pH = 1-3  Ex. Of acid in your body?

Bases  Produces hydroxide ions in solution  Alkaline solutions contain lower concentrations of _______than pure water  pH values = ___________  Strong bases, pH=11-14

Buffers  pH of fluids in cells of human must be kept at  Lower or higher affects the chem. Reactions in the cells  Control pH to maintain homeostasis  Buffers-weak acids or bases that react with strong acids or bases to prevent sudden changes in pH