Bio ch02 chemistry basis
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Bio ch02 chemistry basis

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Bio ch02 chemistry basis Bio ch02 chemistry basis Presentation Transcript

  • KEY CONCEPT All living things are based on atoms and their interactions.
    • refers to anything that has mass and takes up space.
      • 92 naturally occurring elements.
        • Only six make up 98% body weight of organisms.
          • CHNOPS
    • Matter
    • Living and non-living matter consist of atoms of different elements.
    • An atom is the smallest basic unit of matter.
    • An element is one type of atom.
    Hydrogen atom (H) Oxygen atom (O) H O View slide
      • The nucleus has protons and neutrons.
      • Electrons are in energy levels outside nucleus.
    • An atom has a nucleus and electrons.
    Oxygen atom (O) Nucleus: 8 protons (+) 8 neutrons outermost energy level: 6 electrons (-) inner energy level: 2 electrons (-) View slide
    • Atomic Number
      • Number of protons in the nucleus
    • Atomic mass/ mass number
      • Sum of the protons and neutrons in the nucleus
    • Isotopes
      • Atom of the same element having the same atomic number but different mass number due to number of neutrons
  •  
      • water (H 2 O)
    • Elements- 92 naturally occurring and 6 found in living things
    • A compound is made of atoms of different elements bonded together.
    O H H _ + +
      • carbon dioxide (CO 2 )
    • A compound is made of atoms of different elements bonded together.
      • water (H 2 O)
      • many other carbon-based compounds in living things
    • A compound is made of atoms of different elements bonded together.
      • water (H 2 O)
      • carbon dioxide (CO 2 )
    • Ions form when atoms gain or lose electrons.
    • An ion is an atom that has gained or lost one or more electrons.
      • positive ions
      • negative ions
    • Ionic bonds form between oppositely charged ions.
    Sodium atom (Na) Chlorine atom (CI) Sodium ion (Na + ) Chloride ion (CI - ) Na loses an electron to CI ionic bond gained electron
    • Atoms share pairs of electrons in covalent bonds.
    • A covalent bond forms when atoms share a pair of electrons.
      • multiple covalent bonds
      • diatomic molecules
    covalent bonds Oxygen atom (O) Carbon atom (C) Oxygen atom (O) Carbon dioxide (CO 2 )
  • KEY CONCEPT Water’s unique properties allow life to exist on Earth.
    • Life depends on hydrogen bonds in water.
    • Water is a polar molecule.
      • Polar molecules have slightly charged regions.
      • Nonpolar molecules do not have charged regions.
      • Hydrogen bonds form between slightly positive    hydrogen atoms and slightly negative atoms.
    O H H _ + +
  • O H H _ + + O H H _ + + O H H _ + + O H H _ + +
    • Hydrogen bonds are responsible for important properties of water.
    • Properties of Water
      • High heat capacity
      • Large number of hydrogen bonds absorb heat without a large change in temperature.
    • Properties of Water
    • High Heat of Vaporization
      • Large number of hydrogen bonds must be broken to evaporate water.
    • Universal Solvent
    • Cohesive and Adhesive
    • High Surface Tension
    • Many compounds dissolve in water.
    • A solution is formed when one substance dissolves in another.
      • A solution is a homogeneous mixture.
      • Solvents dissolve other substances.
      • Solutes dissolve in a solvent.
    solution
    • “ Like dissolves like.”
      • Polar solvents dissolve polar solutes.
      • Nonpolar solvents dissolve nonpolar solutes.
      • Polar substances and nonpolar substances generally remain separate.
      • Hydrophilic molecules
        • Attract water.
      • Hydrophobic molecules
        • Cannot attract water.
    • “ Like dissolves like.”
    • Some compounds form acids or bases.
    • An acid releases a hydrogen ion when it dissolves in water.
      • high H + concentration
      • pH less than 7
    more acidic stomach acid pH between 1 and 3
    • Frozen water is less dense than liquid water
      • Ice acts as an insulator on top of a frozen body of water.
    • Acids and Bases
    • pH
    • Some compounds form acids or bases.
    • An acid releases a hydrogen ion when it dissolves in water.
      • high H + concentration
      • pH less than 7
    more acidic stomach acid pH between 1 and 3
    • Base
      • either removes hydrogen ions (H + ) or release hydroxide ions (OH - ).
      • low H + concentration
      • pH greater than 7
    bile pH between 8 and 9 more basic
    • A neutral solution has a pH of 7.
    pure water pH 7
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