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Chemicals and Water (Water and Life (acidic and basic conditions (Acids…

- - - - unequal sharing of elections
      - properties of H2O arise from opposites attracting
      - positive attracted to neg
      - Water molecules shape like wide V
        
        H2O- 1 hydrogen, 2 oxygens
        
        held together by covalent bonds
        
        properties of H2O arise from opposites attracting
      - Moderation by temp
        
        Kinetic energy
        
        energy of motion
        
        Atoms and molecules have it bc their always moving
        
        Thermal energy
        
        associated with random movement
        
        reflects total kinetic energy
        
        will move between hot and cold until same temp
        
        Heat
        
        thermal energy in transfer from one body to another
        
        Calorie (Cal) 1cal/(gxC)
        
        Specific heat
        
        amount of heat the must be absorbed or lost
        
        traced back to hydrogen bonding
        
        heat absorbed breaks hydrogen bonds
        
        heat released makes hydrogen bonds
        
        Evaporative cooling
        
        Vaporization
        
        transformation from liquid to gas
        
        fast molecules overcome attractions and become a gas
        
        occurs at any temp
        
        Heat of vaporization
        
        quantity of heat a liquid must absorb to be a gas
        
        H2O has hight heat of evaporation
        
        hydrogen bonds must break for this
        
        Helps moderate earths climate
  - - - Hydrogen bonds holding H2O together
      - Makes H2O more structured
      - contributes to transport of H2O & dissolved nutrients against gravity in plants
      - Adhesion
        
        clinging of one solution to another
        
        helps counter downward pull of gravity
      - Surface tension:
        
        measure of how difficult it is to stretch or break surface of liquid
        
        H2O has unusually high surface tension
    - - expansion upon freezing
        
        Floating ice
        
        Floating caused by hydrogen bonds
        
        Between 4-0 degrees C molecules most slow unable to break hydrogen bonds
        
        important factor in suitability of environment for life
        
        Solvent of life
        
        Solution
        
        a liquid that is a completely homogeneous mixture of two or more substances
        
        solvent
        
        dissolving agent
        
        solute
        
        substance dissolved
        
        Aqueous solution
        
        Water is solvent and solute is dissolved in it
        
        Hydrophilic substance
        
        substance with an affinity to water
        
        doesn't need to dissolve
        
        hydrophobic substances
        
        are nonionic and non polar
        
        don't create hydrogen bonds
        
        repel water
  - - - Acid
        
        increases hydrogen ion concentration
      - Base
        
        decreases hydrogen ion concentration
- - - - anything that takes up space and has mass
      - exist in many forms
    - - element
        
        a substance that cannot be broken down to another substance by chemical reactions
        
        92 elements occurring in nature
      - compound
        
        a substance consisting of two or more different elements combine to a fixed ratio
        
        diff characteristics from elements
    - - 20-25% of elements are essential elements
        
        elements essential to life
        
        oxygen, hydrogen, nitrogen, carbon make up 96% of living matter
      - trace elements
        
        required by an organism in only minute quantities
      - some are toxic
  - - - atoms
        
        smallest unit of life
        
        very small
      - subatomic particles
        
        compose atoms
        
        only three kinds of particles relevant
        
        neutrons
        
        neutrally charged
        
        protons
        
        positivity charged
        
        electrons
        
        negatively charges
        
        protons and neutrons packed togetherin atomic nucleus at center of atoms
      - atomic number and mass
        
        all elements differ in number for subatomic particles
        
        Atomic number
        
        written as a subscript to the left of atomic symbol
        
        tells us the amount of protons and electrons
        
        mass number
        
        total number of protons and neurons in nucleus of atom
      - isotopes
        
        atoms with more neutrons than others giving it a greater mass
        
        when they have diff masses, still chemically behave the same
        
        radioactive isotopes: the nucleus decays spontaneously , giving off particles and energy
      - chemical reactions
        
        chemical reactions
        
        make and breaking bonds, leading to changes in composition of matter
        
        reactants: starting materials products: resulting materials
        
        coefficients indicate number of molecules involved
        
        reactions cannot create or destroy atoms but. can rearrange elections amount them
        
        chemical reactions are reversible
        
        chemical equilibrium
        
        point at which reactions offset one another