Chemical Content of Life

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Chemical Content of Life

• Matter anything that takes up space and has
  mass.
• Mass A measure of the amount of matter an
  object contains .
• What is weight?

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Elements of Lifepage 14 sg

• Carbon, Oxygen , Hydrogen, and Nitrogen 96 of
  living matter.
• Calcium, Phosphorus, Potassium, Sulfur, Sodium,
  Chlorine, Magnesium and trace elements make up
  the remaining 4 of an organisms weight.

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Use of elements in living organisms

• Calcium (Ca) - a macronutrient
• 2 to 3 pounds of our total body weight. building
  and maintaining strong bones and teeth
• helps control muscle growth and the electrical
  impulses in your brain

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Sulpher / S

• Needed to make two of the 20 amino acids

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Iron (Fe) - a micronutrient

• Used to make tendons and ligaments.
• Certain chemicals in our brain are controlled by
  the presence or absence of iron.
• Necessary for heme group on hemoglobin

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Nitrogen (N) - a macronutrient

• role in digestion of food and growth.
• It is also worth noting that in the plant
  kingdom, nitrogen is one of the 3 main elements
  that make plant life possible. (Potassium and
  phosphorus are the other two)

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Phosphorus (P) - a macronutrient

• formation of bones and teeth,
• part of the body's energy storage system( ATP)
• helps with maintaining healthy blood sugar
  levels.
• found in substantial amounts in the nervous
  system.
• The regular contractions of the heart are
  dependant upon phosphorus, as are normal cell
  growth and repair

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Sodium (Na)

• important part of blood plasma.
• Maintain correct amount of water in our blood.
• allows our muscles to contract
• Normal functioning of our nervous system

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Trace elements

• Elements required by an organism is small
  amounts.
• Indispensable for life.
• Headstart in Biology - elements in body

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THE ATOM
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Atoms are made of subatomic particles

• Atomic structure (ann, go to first animation)
• Life  eLearning

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Atomic Number and Atomic Weight

• Atomic Number is the number of protons.
• In an atom the number of protons is equal to the
  number of electrons.

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Mass Number

• The number of protons and neutrons of a
  particular element.
• Can deduce the number of electrons
• Number of neutrons can vary but not the number of
  protons

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Isotopes

• CHE1.3-b-Isotopes
• Atoms of an element that have the same atomic
  number but different mass number.

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Radioactive isotopes

• Radioactive atoms vary in their stability
• they break down or not so likely, and each is
  measured in half-lives
• how long it takes for half a starting amount to
  break down. 
• used to determine how long ago a material with a
  radioactive substance in it formed
• (you add up the remaining radioactive materials
  plus their breakdown products to figure out how
  much was there originally).

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• Many elements have multiple isotopes, some of
  which may be radioactive. Radioactive isotopes
  are characterized by a constant rate of decay
  into other elements or isotopes.
• Common isotopes.

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Bonding

• There are several types of bonds which you need
  to know about.
• First is the covalent bond -two atoms share
  electrons.
• Animation Quizzes- ( ann go to covalent bonds)

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Ionic bonds

• Ionic bonds are formed as attractions between
  ions of opposite charge, such as those in sodium
  chloride.
• Animation Quizzes (ann go to ionic bonds)

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Hydrogen bonds/ pg 13sg

• This type of bond is formed in water. The water
  molecule has a slightly negative end and a
  slightly positive end.
• We can see the result of hydrogen bonds with
  water
• Shockwave (ann go to hydrogen bond animation)
• We will look at water closely as it is vital to
  life

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• Water forms hydrogen bonds. It is the number of
  bonds formed which gives water many of its
  properties

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Polar covalent bonds

• The figure is a diagrammatic representation of a
  water molecule having polar covalent bonds
  between the Oxygen atom and the Hydrogen atoms.

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Read this

• In a polar covalent bond, the electrons shared by
  the atoms spend a greater amount of time, on the
  average, closer to the Oxygen nucleus than the
  Hydrogen nucleus. This is because of the geometry
  of the molecule and the great electro negativity
  difference between the Hydrogen atom and the
  Oxygen atom.
• The result of this pattern of unequal electron
  association is a charge separation in the
  molecule, where one part of the molecule, the
  Oxygen, has a partial negative charge and the
  Hydrogens have a partial positive charge.

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• Water is not the only molecule that can have
  polar covalent bonds. Examples of other molecules
  that have polar covalent bonds are Peptide bonds
  and amines .
• The biological consequence of polar covalent
  bonds is that these kinds of bonds can lead to
  the formation of a weak bond called a hydrogen
  bond.

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Water/pg 13 sg

• Properties of water
• Resource The World of Chemistry ( go to right
  top to open video page then go to video 12
• The Open Door Web Site IB Biology Water

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Properties of waterTransparency

• Light can pass through water

• Allows certain structures to perform. Like
  photosynthesis in plants, the retina of the eye.
• Allows aquatic organisms to have access to light

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adhesion

• Adhesion of water to sides of glass creating a
  meniscus.

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cohesion

• Water is attracted to water. (polar) creating
  drops.

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• The oxygen end of water has a negative charge and
  hydrogen end has a positive charge. The hydrogens
  of one water molecule are attracted to the oxygen
  from other water molecules.

• This attractive force is what gives water its
  cohesive and adhesive properties.

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Surface Tension

• Surface tension cohesion of water molecules at
  the surface of a body of water. Costa Ricas
  Jesus Christ Lizards - How they walk on water
  Eco Interactive Costa Rica

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Surface tension

• essential for the transfer of energy - create
  waves.
• rapid oxygen diffusion in lakes and seas.
• Importance to life of aquatic organisms.

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Capillary Action

• Surface tension is related to the cohesive
  properties of water.
• Capillary action however, is related to the
  adhesive properties of water.

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Cohesive property
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Solvent Properties

• Many different substances dissolve in water
  because of its polarity.
• Inorganic sodium ions
• Organic sugar

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Water as a Solvent 

• The partial charge that develops across the water
  molecule helps make it an excellent solvent. 
  Water dissolves many substances by surrounding
  charged particles and 'pulling' them into
  solution.

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Terms to know

• Solution liquid that is a homogenous mix of 2
  or more substances
• Solvent dissolving agent
• Solute substance that is dissolved
• Aqueous solution one in which water is solvent

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• For example, common table salt, sodium chloride,
  is an ionic substance that contains alternating
  sodium and chlorine ions.

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• When table salt is added to water, the partial
  charges on the water molecule are attracted to
  the Na and Cl- ions.

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• substance that carries a net electrical charge,
  including both ionic compounds and polar covalent
  molecules can dissolve in water. 
• Oil is a non-polar molecule. 
• no net electrical charge across an oil molecule
• not attracted to water molecules and, therefore,
  it does not dissolve in water.

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Heat Capacity (water)

• Water has large heat capacity
• Large amts of nrg to raise temp
• Nrg needed to break hydrogen bonds

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• For life the temperature of water tends to
  remain quite stable. Good for aquatic life.
• Blood which is made primarily of water can carry
  heat from a warmer part of the body to cool it.
• Blood is used as transport medium

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Freezing Point (thermal property water)

• Water freezes at high temperatures, but becomes
  less dense as it cools to freezing point, ice
  forms at the surface first
• This is of biological importance as the ice
  insulates the water underneath, so living
  organisms can survive

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Cooling effect of evaporation (thermal property
water)

• Water can evaporate at temperatures below boiling
  point. Hydrogen bonds have to be broken t do
  this. The heat energy needed to break the bonds
  taken from the liquid water, cooling it down.
• Evaporation from plants and skin have useful
  cooling effects.

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Think of pH as "water balance."

• water breaks apart into two halves  a hydrogen
  ion (H) and a hydroxide ion (OH-). 
• Notice that if you put the hydrogen and hydroxide
  ions back together, you will restore H2O
• For a video regarding this concept
• Resource The World of Chemistry go to right
  top, open video and go to 16

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• water molecules breaks.   But, even when all are
  broken, the concentration (represented by
  brackets, ) of hydrogen ions remains the same
  as the concentration of hydroxide ions. 

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• concentration of hydrogen ions is the same as the
  concentration of hydroxide ions (H OH-). 

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• pH from 0 to 6.9 is an acid
• solution with a pH from 7.1 to 14 is a base (can
  also be called an "alkaline" solution). 
• Acids and bases do not have an even balance of
  hydrogen ions with hydroxide ions.  Acids have
  more hydrogen ions, while bases have more
  hydroxide ions. 

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Acids

• Acids are ionic compounds ( a compound with a
  positive or negative charge) that break apart in
  water to form a hydrogen ion (H).The strength
  of an acid is based on the concentration of H
  ions in the solution. The more H the stronger
  the acid.
• Example HCl (Hydrochloric acid) in water

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Characteristics of Acids

• Acids taste sourAcids react strongly with
  metals (Zn HCl)Strong Acids are dangerous
  and can burn your skinExamples of Acids1.
  Vinegar 2. Stomach Acid (HCl)

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Bases

• Bases are ionic compounds that break apart to
  form a negatively charged hydroxide ion (OH-) in
  water.The strength of a base is determined by
  the concentration of Hydroxide ions (OH-). The
  greater the concentration of OH- ions the
  stronger the base.

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• Example NaOH (Sodium Hydroxide-a strong base) in
  water Solutions containing bases are often
  called alkaline.

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Characteristics of Bases

• Bases taste bitterBases feel
  slipperyStrong bases are very dangerous and
  can burn your skinExamples1. lye (Sodium
  Hydroxide)2. Ammonia

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Every step of the pH scale is a tenfold change in
concentration!

• The pH scale is odd.  Who ever heard of a scale
  going from 0 to 14?  Why is 7 neutral?  The
  reason it is so odd is because the concentration
  of these ions is measured on a logarithmic scale,
  not a regular scale.  That is, a pH of 5 has ten
  times as many hydrogen ions in it as a pH of 6.

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• Our bodies are extremely sensitive to blood pH. 
  Any blood pH more acidic than 6.8 or more basic
  than 8.0 causes death. 

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Buffers

• Go to making a buffer Untitled Document

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Acid base buffer

• Go to acid base pH tutorial AP Chemistry
  Resources

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Redox rections

• This is a very important part of biology.
• Electrons lost must be gained
• Oxidation-Reduction.

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