Chapter 2 Chemical Content of Life

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Chapter 2 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 Life Topic 2.1.1

• Carbon, Oxygen , Hydrogen, and Nitrogen make up
  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 2.1.2

• Calcium (Ca) - a macronutrient
• most abundant elements in our bodies and accounts
  for 2 to 3 pounds of our total body weight.
• is important in building and maintaining strong
• control things like muscle growth and the
  electrical impulses in your brain
• Necessary structural component of bones

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Iron (Fe) - a micronutrient

• This element is used by the body to make tendons
  and ligaments.
• for maintaining a healthy immune system
• Hemoglobin contains iron
• Critical for chlorophyll formation and
  photosynthesis in plants

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Nitrogen (N) - a macronutrient

• It plays an important 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, and
  you may hear them referred to collectively as
  N-P-K whenever talking about key plant
  nutrients.)
• In plants and animals it is used to make proteins

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Phosphorus (P) - a macronutrient

• formation of bones and teeth,
• maintaining healthy blood sugar levels. found in
  substantial amounts in the nervous system.
• regular contractions of the heart are dependant
  upon phosphorus
• normal cell growth and repair

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Phosphours plant and animal

• In both plants and animals phosphorus is an
  essential part of sugar phosphate
• involved in respiration and energy transfer via
  adenosine triphosphates (ATP)
• and is a part of ribonucleic acid (RNA),
  deoxyribonucleic acid (DNA), and membrane
  phospholipids

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Sodium (Na)

• important part of blood plasma.
• maintain the right blood chemistry and the
  correct amount of water in our blood.
• Muscle contractions
• 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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Atoms Topic 2.1.4

• Atomic structure determines the behavior of an
  element
• Atom smallest possible unit of matter that
  retains the physical and chemical properties of
  its element

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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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Ion Topic 2.1.4

• When the number of electrons changes in an atom,
  the electrical charge changes. If an atom gains
  electrons, it picks up an imbalance of negatively
  charged particles and therefore becomes negative

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• If an atom loses electrons, the balance between
  positive and negative charges is shifted in the
  opposite direction and the atom becomes positive.
  
• the magnitude (1, 2, -1, -2, etc.) of the
  electrical charge will correspond to the number
  of electrons gained or lost.
• Atoms that carry electrical charges are called
  ions
• CHE1.3-a-Ions ( ion animation)

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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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• 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- you must understand the different types
of bonds.

• 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 Topic 2.1.5

• 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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Topic 2.1.5 Water

• 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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• 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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Properties of Water Topic 2.1.5

• Properties of water
• The Open Door Web Site IB Biology Water

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Properties of waterTransparency Topic 2.1.6

• 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 and Cohesion

• Water is attracted to other water. This is called
  cohesion. Water can also be attracted to other
  materials. This is called adhesion.

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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 is the name we give to the
  cohesion of water molecules at the surface of a
  body of water. Water ( scroll to jesus lizard)

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• Surface tension is essential for the transfer of
  energy from wind to water to create waves. Waves
  are necessary for rapid oxygen diffusion in lakes
  and seas.

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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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• any substance that carries a net electrical
  charge, including both ionic compounds and polar
  covalent molecules (those that have a dipole),
  can dissolve in water. 
• Oil is a non-polar molecule. 
• no net electrical charge
• not attracted to water molecules and, therefore,
  it does not dissolve in water.

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Heat Capacity (water)

• Water has the highest specific heat of all
  liquids except ammonia. As water is heated, the
  increased movement of water causes the hydrogen
  bonds to bend and break. As the energy absorbed
  in these processes is not available to increase
  the kinetic energy of the water, it takes
  considerable heat to raise water's temperature.

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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.

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Boiling (thermal property water)

• As water is heated, much of the energy is used to
  bend the hydrogen bonds a factor not available
  in the solid or gaseous phase. This extra energy
  causes the specific heat to be greater in liquid
  water.
• Or it takes a great deal of energy to boil water.

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• This is significant to life because many living
  creatures could not survive it blood were easy to
  boil.
• Natural aquatic habitats remain safe from
  overheating

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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 to 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.required in other
topics

• Water is H2O
• 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

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• 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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• what I mean by "water balance" is that the
  concentration of hydrogen ions is the same as the
  concentration of hydroxide ions (H OH-). 

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• A solution with a pH from 0 to 6.9 is an acid,
  while a 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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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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• Understanding pH
• pH, the Power of Hydrogen

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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 react strongly with metals (Zn HCl)
• Strong Acids are dangerous and can burn your skin
  
• taste sour
• Examples of Acids1. Vinegar 3. Citrus Fruits
  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 bitter
• Bases feel slippery
• Strong bases are very dangerous and can burn your
  skin
• Examples1. lye (Sodium Hydroxide)2. Ammonia

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Buffers

• Buffer solutions are solutions which resist
  change in hydrogen ion and the hydroxide ion
  concentration (and consequently pH) upon addition
  of small amounts of acid or base, or upon
  dilution. Buffer solutions consist of a weak acid
  and its conjugate base (more common) or a weak
  base and its conjugate acid (less common).

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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 reactions part of topic 7

• This is a very important part of biology.
• Electrons are not transferred to the surroundings
  in ordinary chemical reactions but electrons lost
  by one species, must be gained by another. Such
  chemical reactions involving loss of electrons by
  one species and the simultaneous gain by another
  constitute (oxidation - reduction) redox
  reaction.

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