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 H 2 O H + + OH - (Hydroxide ion) H + + H 2 O H 3 O + (Hydronium ion) If hydronium ions are greater solution is acidic

Acidic H 3 O + (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