energy and matter including unique water properties
TRANSCRIPT
Energy and Matter
Including Unique Water Properties
Energy
• All living things use energy• Amount of energy in universe remains the
same but can change form• Defined as the ability to do work
States of Matter• Atoms and molecules are in constant motion• Motion and spacing determine– Liquid• Fixed volume and flowing shape
– Solid• Fixed volume and shape
– Gas• Fill volume of container and no attraction between
particles
Energy and Chemical Reactions(Metabolism)
• Chemical Reaction– Substances change to produce different
substances– Energy absorbed or released (bonds)– Reactants (left) and Products (right)
Activation Energy
• Amount of energy needed for a chemical reaction to begin
• Catalysts “jump start” the reaction– Reduces amount of energy needed– Enzymes, proteins or RNA molecules
Oxidation Reduction Reactions
Water and Solutions
• In comparison to a jellyfish, our bodies are both made up of cells composed mostly of water.
• Chemical reactions occurs in aqueous solutions
Polarity• Water molecule – Hydrogen shares electrons with oxygen– Hydrogen bonds are formed at an angle– Negative charge on oxygen and positive charges
on Hydrogen create a polar compound
Solubility of Water
• Polar can dissolve other polar substances• Dissolved substances are found in all living
things • Essential to maintain normal body functions– Muscle contractions– Nerve impulses
Hydrogen Bonding• Hydrogen bonds allow water molecules to
“cling” to each other & other substances• Provide the unique properties of water– Adhesion– Cohesion– Absorption and retention of heat– Cooling properties through evaporation– Density of ice– Ability to dissolve other substances
Cohesion
• Water molecules stick to each other– Surface tension
Adhesion
• Attraction to different substances– Glass molecules and water– Capillary action
Temperature Moderation• Absorb or release large amounts of energy with
just a slight change in its own temperature– Specific heat– Hydrogen bonds
• Water can absorb large amount of energy from sun during the day and slowly release it at night– Oceans stabilize Earth’s temperature– Organism’s can keep cells at even temperature
despite changes in the environment
• Evaporative cooling– Liquid evaporates taking heat with it – Remaining liquid is cool– Prevents overheating of land organisms
Density of Ice
• Solid water is less dense than liquid• Shape of water molecule & hydrogen bonding• Angle between hydrogen atoms so wide that
open spaces are formed as it becomes solid• Ice floats– Ponds and lakes freeze top down– Important for aquatic organisms
Acids and Bases• Ionization of water– Water molecules move– Collisions occur & some strong enough to knock off
a Hydrogen atom– The loose Hydrogen then joins another water
molecule• H2O <-> H+ + OH- (Hydroxide ion)• H+ + H2O <-> H3O + (Hydronium ion)• If hydronium ions are greater solution is acidic
• Acidic• H3O + (Hydronium ion)• Sour taste and highly corrosive
• Basic or Alkaline• OH- (Hydroxide ion)• Bitter taste and slippery
• pH scale (0 acidic, 7 neutral, 14 basic)• Buffers– Chemical substances used to neutralize small
amounts of either an acid or base