The Chemistry of Life - PowerPoint by pengtt


									  Introduction to Basic
  Allorganisms (living things)
  are composed of chemicals.

•The study of these chemicals &
how they react in living organisms
is called biochemistry
  Introduction to Chemistry
• The smallest
 components that
 make up cells are
• Atoms are “pure”,
 meaning they are
 only made up of
 one kind of
 substance or
                                atomos “unable to be cut”.
Has 3 subatomic
1.neutrons (no charge)
2.protons (+)
3.electrons (-) arranged
in levels (shells)

  Protons & neutrons have approx. the same mass
  and comprise the nucleus.
  Electrons are 1/1840th the mass of a neutron
  and travel constantly in the space around the
  nucleus (the electron cloud)
  Name coined by John Dalton in 1805.
        The Electron Cloud

The electrons travel at almost the speed of light.
They create a “cloud” around the nucleus.
          More Important Info.

 Atomsthat combine
 chemically create
               Periodic Chart

 118 elements are represented on the
 newest periodic table of elements.
 Elements are represented by one or two
 letter symbol. Ex. Carbon (C), Helium (He)

   Elements song;
               Element Information

The element info. is not always in the same order within the element box.
Element Information:
      Fill in

          A=   atomic number (# protons)

               ion charge(s) (electron
          B=   affinity)

          C=   Element symbol

          D=   Element name

          E=   Atomic mass (protons +
             –   Elements (and symbols)
             –   Atomic Number (# of protons)
             –   Atomic Mass (# of protons + neutrons)
             –   Phase of Element at Earth temperature
             –   Affinity for giving or taking electrons

 “CHNOPS” -97% of the
 compounds present in living
 organisms contain these 6
• All atoms are neutral so the # of protons
  (the atomic number) is equal to the # of

     # of P = # of E
           Energy Levels of Atoms
  1. An electron shell is sometimes called an orbital or energy
  2. Shells are areas that surround the nucleus of an atom.
  3. Electrons are found on the energy shells.
  4. Each of those shells (levels) has a name.

• There are a couple of ways that atomic orbitals are named.
  Chemists use letters to name the orbitals around a nucleus.
  They use the letters "k,l,m,n,o,p, and q".
• The "k" shell is the one closest to the nucleus and "q" is the
  farthest away.
• The further from the nucleus, the more energy the electron has.
 # Of Electrons In Each Shell

• Not all shells hold the same number of
  electrons. For the first eighteen elements,
  there are some easy rules.
  Electrons and Energy Levels

• The first shell is located closest to the
  nucleus and can hold a maximum of 2
  electrons (e-)


      Hydrogen               Helium
 # Of Electrons In Each Shell

• The 2nd shell (l-shell) only holds a max. of
  eight electrons.
• The 3rd shell (m-shell) only holds a max. of
  eight valance electrons (for the first
  eighteen elements). The m-shell can
  actually hold up to 8 valance and 10 sub-
  active electrons
• The maximum number of electrons you
  will find in any shell is 32.
• Using your Orbital handout, draw the
  appropriate # of electrons on the orbital(s)
  for the first 18 elements.

• you must fill the first orbital (with 2 e-)
  before you can go to the second orbital.
• You must fill the second orbital (with 8 e-)
  before you can go to the 3rd orbital.
The answers are:

 This way of drawing the electrons is called the Electron Dot Formula
When using the Lewis Dot Formula, you only show the
electrons in the outer most shell.
These are called VALANCE electrons.
1. Variation in # of neutrons of an element
2. Changes mass number
3. Can be radioactive
     Nuclei are unstable and break down at a
          constant rate over time

Non-radioactive carbon-12 (6e-, 6 p+, 6n).
Non-radioactive carbon-13 (6 e-, 6 p+, 7n).
Radioactive carbon-14 (6 e-, 6p+, 8n)

All isotopes of an element have the same
chemical properties (because they all have
the same # of e- and protons+)
Uses of Radioactive Isotopes
1. To study living systems/processes

  ex: Radioisotopes can be used to help understand
  chemical and biological processes in plants.
  (radioactive water)
Uses of Radioactive Isotopes
2. Diagnose and treat disease (nuclear medicine)
 a) Tracers:
 Bone scans can detect the spread of cancer six to 18
 months sooner than X-rays by using a PET scan, for ex.
 FYI: The most common tracer is a radioactive version of
 glucose. When this is injected into your body it travels to
 places where glucose is used for energy. It shows up
 cancers because they use a lot of glucose. It will also be
 taken up by normal tissues which use glucose for energy, for
 example the brain, and as a result of other abnormalities
 such as infection. The PET scan shows cancerous hot spots.
 In other words, cancer tumors light up.
Uses of Radioactive Isotopes
2. Diagnose and treat disease             (continued)

   b) Drug Testing:

One of the main tests is to determine if the pharmaceutical is
   going to other parts of the body than the intended target
   and what effect it has on the non-target areas. By adding
   a radioactive tag to the pharmaceutical, researchers can
   pinpoint all parts of the body and the concentration that
   accumulates in non-target areas. From this they can
   determine if there is likelihood of adverse reactions in
   other parts of the body.
        Uses of Radioactive Isotopes

   3. sterilize food: Food irradiation is a method
    of treating food in order to make it safer to
    eat and have a longer shelf life.

Food   irradiated by exposing it to the gamma rays of a radioisotope -- one
that is widely used is cobalt-60. The energy from the gamma ray passing
through the food is enough to destroy many disease-causing bacteria as well
as those that cause food to spoil, but is not strong enough to change the
quality, flavor or texture of the food.
 Uses of Radioactive Isotopes

   calculate the age of certain rocks
 4.
 and fossilized organisms:

• Your whole goal as an atom is to
  become a "happy atom" with
  completely filled electron
• Sometimes that means you need
  to give up some electrons or
  maybe gain some electrons

• Atoms that have 1, 2 or 3
  electrons in the outer most
  shell, will GIVE THEM AWAY!
• Atoms that have 5, 6 or 7
  electrons in the outermost shell
  will steal electrons from other
            Ionic Bond
• Now, Na+ and Cl- are attracted to one
  another because….OPPOSITES ATTRACT!

                     NaCl is now neutral
                     and makes up what
                     we commonly call….
                     TABLE SALT!
              For example:
• O----------- O2-

                         Adding 2 more
                         electrons will give
                         Oxygen a full
                         outermost shell but it
                         will also make oxygen
                         have a negative
                         charge (since it now
                         has 10 electrons but
                         still only 8 protons).
    Make these atoms into ions
•   Be        Be 2+
•   F
•   Al
              Al 3+
•   Mg
•   S         Mg 2+
              S 2-
              Have you ever heard of
• Electrolyte is a
  "medical/scientific" term for
  salts, specifically ions.              • Electrolytes are important
• The term electrolyte means that          because they are what your
  this ion is electrically-charged.        cells (especially nerve,
• For example, your body fluids --         heart, muscle) use to
  blood, plasma, interstitial fluid        maintain voltages across
  (fluid between cells) -- are like        their cell membranes and to
  seawater and have a high                 carry electrical impulses
  concentration of sodium                  (nerve impulses, muscle
  chloride (table salt, or NaCl).          contractions) across
                                           themselves and to other


The major body electrolytes are as follows:
sodium (Na+), potassium (K+), chloride (Cl-), calcium (Ca2+)
magnesium (Mg2+), bicarbonate (HCO3-), phosphate (PO42-), sulfate (SO42-)
   Compounds are groups of two or more elements that
    are bonded together. There are two main types of
    bonds that hold those atoms together:
      Ionic compounds happen when electrons are
       donated from one atom to another. Atoms that
       have 1, 2, 3, 5, 6 or 7 electrons in their
       outermost orbital (except for the first level)
       tend to transfer electrons forming ions.
      Covalent compounds happen when the atoms
       share the electrons. Atoms that have 4 or 5
       electrons in their outermost orbital tend to
       share electrons making covalent compounds.
               Covalent Bonds
   A chemical bond formed by the sharing of
    electrons in the outermost shell of both (all)
   Atoms change their physical and chemical
    properties when they form a compound via
    covalent bonding.
   Covalent bonds can be single (one pair of
    electrons is shared) double (two pairs), triple
    (three pairs), quadruple (four pairs)
                                 Let’s take a look….
             NaCl and H2O

• 1 Oxygen and 2 hydrogen share their
 outermost electrons so each can have a
 full outermost shell.

                                 H       H

                               Water can also
                               be written as
                                above. The
                                 single line
                                represents a
                                single bond.
• Molecules are made up of atoms that have been
  chemically combined.                          H2O
• Molecules may be made from:
     • more than one type of atom (Ex. H2O), or
     • atoms of the same type. (Ex. Hydrogen covalently bonds to one
       another and is found naturally in pairs; H2)

• The number of atoms in each element in a molecule
  is shown by a subscript following the symbol for the
  element. Ex. CO2 (one carbon, 2 oxygen)

• Water can be broken down into two very different
  substances, hydrogen and oxygen.
• Hydrogen and oxygen are elements (substances
  that cannot be broken down chemically into simpler
Single Bonds:   one, two, three, or four

                          H            H

           More Covalent bonds

   Double: 2 pairs of electrons are being shared
 Triple bond: 3 pairs being shared
• Quadruple bond : two carbon atoms

               C C
        Lewis Dot Structure
• When drawing the electrons using the
  Lewis Dot Formula, you do not draw the
  outer ring.
• When showing a bond, you only use a
                               This is
     Atom 1   Atom 2
                               how to show
                               the bond
                               between two
                               oxygen atoms.
• Relatively weak attractive forces
  between electrically neutral
  atoms and molecules.
• These forces are not as strong as
  ionic bonds or covalent bonds.
• They can hold together and create
  a “sticky” or adhesive property.
• Ex. Geckos walking up a glass
Atoms, Molecules, and Compounds

   Water may vary between gas, liquid
    and solid while keeping the same
    chemical composition.
 All  living things are
    composed of
    approximately 70 to
    80% water.

   Water has some unusual physical
    & chemical properties that have
    had a powerful effect on the
    evolution of life.
    (we’ll talk about that later)
           Hydrogen Bonding
• Polarity: an uneven sharing of electrons.
           Hydrogen Bonding
 The negative part of one water molecule will
  attract the positive parts of other, nearby water
 This is why water falls from the sky as raindrops,
  and not individual molecules, or why water tends
  to bead up on the hood of your freshly waxed
  car, or why you can cause water to bulge out
  over the rim of a glass if you fill it carefully; the
  molecules are all pulling together.
Cohesion and Adhesion of Water
• In hydrogen bonding, water sticks to other water
  molecules. This is called COHESION.

• Water molecules are also attracted to other polar
  substances causing them to adhere to many kinds
  of materials.
• Water sticking to other substances is ADHESION.
                      Surface Tension
    The water molecules bond together at the
     surface creating a surface "film“ or tension.
But those on the
surface have no
neighboring atoms                                         The cohesive
above, and exhibit                                      forces between
stronger attractive                                    molecules down
forces upon their                                      into a liquid are
nearest neighbors                                       shared with all
on the surface.                                           neighboring
                                                            atoms so
                                                         they’re not so
This enhancement of the attractive forces at the surface is called
                       surface tension.
Soaps and detergents lower the surface
 tension of the water (breaking the surface
 tension much quicker). Things that could
 walk on the surface cannot if the water
 becomes soapy or polluted.

Washing your hands:
Soap molecules are attracted to both water and
 oil. One end of the soap molecule sticks to
 oil, the other end sticks to water. The soap
 breaks up the surface tension and keeps the
 oil drops mixed in with the water so that the
 oil can wash off your hand.
        Adhesion or Cohesion?

• Adhesion – water sticking to the sides of the glass
• The photograph below shows water on the
  roof of a waxed car. The water molecules
  cling to each other but not to the waxed
  surface because the wax is non-polar.

          Adhesion or Cohesion?
• This water strider is able to remain on the
  surface of water because of hydrogen bonding
  between the molecules. The insect is light and
  it’s weight is spread over the water so that there
  is not much weight at any one point.
                                      The Jesus Lizard:

Polar vs. Non-polar:   Ions and Polar Molecules Dissolve in Water

 • One reason polarity is important is because water
   can bond to other polar molecules; hence water is
   often called the universal solvent.
A good
example of this                              Oil and water
is the addition                              do not mix
of sugar to                                  because oil is
water. Because                               non-polar and
sugar is also a                              therefore
polar molecule,
                                             doesn’t have
the positive end
of the water                                 a positive or
joins to the                                   negative
negative end of                              side.
sugar and vice
            Exception to the Rule
• Salt is an example of an exception to this. Salt is a
  non-polar molecule, yet water can dissolve it.
• Salt dissolves in water because it breaks down into
  ions in solution. It becomes Na+ and Cl- ions that the
  water molecules attach to.
 In the previous example, the salt (NaCl)
 becomes dissolved in the water, forming a
 solution. A solution is composed of a
 substance dissolved in another substance.
The substance dissolved is
  the solute and the
  substance that dissolves
  the solute is a solvent.
In this example, the solvent is
  water and the solute is salt.
A solution in which water is
  the solvent is called an
  aqueous solution.
Dissociation of Water
• The force between water molecules is so
  strong that the oxygen of one water
  molecule can remove a hydrogen atom
  from another water molecule. The water
  molecule, therefore, breaks apart.
• This is called dissociation of water.
• H2O  H+ + OH-
• The free H+ ion can react with another
 water molecule.

• H+ + H2O  H3O+

• H3O+ This is called a hydronium ion
• The pH scale is a measurement system that
  indicates the concentration of hydronium ions
  (H30+) in a solution (compared to hydroxide)
  ions) (OH- ).
• Hydrogen ions are used as the basis of the pH
  scale because they are an important factor in
  many chemical reactions.
• The letters “pH” stand for potential of Hydrogen.
• This term was introduced in 1909 by the Danish
  chemist, Soren Sorensen.
            Acids and Bases
• If the # of H30+ > # of OH- = acid.
• If the # of H30+ < # of OH-, = base (alkaline)
• If the # of H30+ = # of OH-, neutral solution.
pH and your diet

           REDOX Reactions
• are a family of reactions that are concerned
  with the transfer of electrons between atoms.
• Oxidation describes the loss of electrons.
• Reduction describes the gain of electrons.
• Redox reactions are a matched set -- you don't
  have an oxidation reaction without a reduction
  reaction happening at the same time.
• For atoms in their elemental form, the oxidation
  number is 0.
• For ions, the oxidation number is equal to their
  charge. For ex: the oxidation # of oxygen is 2-..
• Because oxygen is unstable (needs 2 more
  electrons), it is “ACTIVELY” hunting for electrons.
ful lifestyles can
release active
oxygen into your
Active oxygen steals
electrons from
healthy cells forming
“free radicals”.
Free radicals then
steal electrons from
other healthy cells.
In turn, these cells
steal electrons from
other cells and so on
and so on…
• UV rays trigger free radicals, destructive
  molecules that act like little darts, poking
  holes in skin's support structure that lead
  to lines and sagging.
                    Free radicals
• Each free radical is capable of destroying an
  enzyme, protein molecule or a complete cell.
  These reactive substances can damage cell
  structures so badly that immunity is impaired and
  mutate DNA codes.
• They can combine and react chemically with other molecules
  that they were not meant to combine with. This process is
  called oxidation.
• Free radicals also speed up the process of aging,
  such as the breakdown of collagen. In addition,
  because they react with oxygen, free radicals may
  reduce the oxygen supply to your cells.
• Every second of our lives billions of free radicals wage
  war in our bodies. This seriously compromises the
  immune system which threatens our vitality.
Common dietary causes of
     free radicals

• Refined sugar* see next slide
• Food additives
• Refined flour and other grain products (corn, pasta)
• Moldy foods (blue cheese)
• Prepared foods (high in both sugar and
• Foods cured in nitrites (bacon, sausages, salami etc)
• Foods high in pesticides (non-organic produce)
• Hydrogenated vegetable oils, margarine etc.
How can we stop free radicals from
 damaging our bodies???

You need to increase the amount of anti-
 oxidants in your diet!
More Best Sources of High Antioxidants

   Berries (Cherry, blackberry, strawberry,
raspberry, crowberry, blueberry, bilberry/wild
   blueberry, black currant), pomegranate,
  grape, orange, plum, pineapple, kiwi fruit,
   Kale, chili pepper, red cabbage, peppers,
parsley, artichoke, Brussels sprouts, spinach,
           lemon, ginger, red beets.
      Dry Fruits high in antioxidants
            Apricots, prunes, dates.
     Broad beans, pinto beans, soybeans.
                Nuts and seeds
   Pecans, walnuts, hazelnuts, ground nut,
                sunflower seeds.
           Barley, millet, oats, corn.
          cloves, cinnamon, oregano
 The pH scale ranges
    from 0 to 14.
   Acidic solutions range
    from 0 to 6
   Basic (Alkaline) solutions
    range from 8 to 14
   Neutral solutions (such
    as pure water) are 7 on
    the pH scale.
   Using the pH scale
    handout, place the
    following examples on
    the scale:
•Buffers are chemical substances
that neutralize small amounts of
acids or bases in a solution.
 If our body’s pH fluctuates too
much, our organs will begin to shut
down and we will die.

•Bicarbonate is one of the body's
 major buffers. Tums and other
 antacids are buffers which
 neutralize the acid in your
•The active ingredient in
aspirin is acetylsalicylic acid.
Why would doctors
recommend buffered aspirin
for some people, especially
those who have a “sensitive”
            Carbon Bonding
• Carbon bonds easily and often with other
  carbon molecules, forming:

• Straight chains:                  Rings:

• Branched chains:
If something has carbon in it, it is called organic.
     Carbon bonding continued..
• Carbon needs 4 more electrons in its valence
  shell to become stable. (Octet rule)
• As mentioned, carbon atoms often bond with
  other carbon atoms but also with hydrogen
  atoms too.
• Carbon can make single, double or triple bonds.
                                    These are in
                                    cigarette smoke!

                   Benzene :
                            FYI: Acetylene
•   Its combustion in pure oxygen produces the highest achievable flame temperature,
    over 3300 °C, allowing it to weld, cut, braze and solder metals in various
    environments: from great depths underwater to the extreme cold of Alaska. The oxy-
    acetylene torch is used to repair ships underwater, to construct bridges, pipelines,
    dams, tunnels, buildings and to reinforce concrete.
•   When the following chemicals are added to acetylene, this is what can be made:

•   Hydrogen chloride ; pipe, siding, rain gutters, molded bottles, electrical insulation, floor and wall
    coverings, upholstery, garden hoses and waterproof clothing.

•   Hydrogen cyanide: rubbers, acrylic fibers, and insecticides.

•   Acetic acid : films and lacquers.

•   Alcohol : vinyl ether used as an anaesthetic.

•   Water : used as a solvent and flavoring in food, cosmetics and perfumes.

•   Chlorine : used as a solvent for fats, phenol and camphor.

•   Formaldehyde: makes resins including urethane foams for cushioning material, carpet underlay
    and bedding, insulation in refrigerated appliances and vehicles, sealants, caulking and adhesives.

•   Acetylene reacts with carbon monoxide and alcohol forming acrylate esters used in the
    manufacture of Plexiglass and safety glasses.

                  FYI: Benzene
• Some industries use benzene to make
  other chemicals which are used to make
  plastics, resins, and nylon and synthetic
• Benzene is also used to make some
  types of rubbers, lubricants, dyes,
  detergents, drugs, and pesticides.
• Natural sources of benzene include
  volcanoes and forest fires.
• Benzene is also a natural part of crude
  oil, gasoline, and cigarette smoke.
    A partial list of the 599 additives approved by
         the US Government for use in the
              manufacture of cigarettes
   Benzene (petrol additive)
    A colorless cyclic hydrocarbon obtained from coal and
    petroleum, used as a solvent in fuel and in chemical manufacture
    - and contained in cigarette smoke. It is a known carcinogen and
    is associated with leukemia.
   Formaldehyde (embalming fluid)
    A colorless liquid, highly poisonous, used to preserve dead
    bodies - also found in cigarette smoke. Known to cause cancer,
    respiratory, skin and gastrointestinal problems.
   Ammonia (toilet cleaner)
    Used as a flavoring, frees nicotine from tobacco turning it into a
    gas, found in dry cleaning fluids.
   Acetone (nail polish remover)
    Fragrant volatile liquid ketone, used as a solvent, for example,
    nail polish remover - found in cigarette smoke.
    A partial list of the 599 additives approved by
    the US Government for use in the
    manufacture of cigarettes
   Nicotine (insecticide/addictive drug)
    One of the most addictive substances known to man, a
    powerful and fast-acting medical and non-medical poison.
    This is the chemical which causes addiction.
   Carbon Monoxide (CO) (car exhaust fumes)
    An odourless, tasteless and poisonous gas, rapidly fatal in
    large amounts - it's the same gas that comes out of car
    exhausts and is the main gas in cigarette smoke, formed
    when the cigarette is lit.
   Tar
    Particulate matter drawn into lungs when you inhale on a
    lighted cigarette. Once inhaled, smoke condenses and about
    70 per cent of the tar in the smoke is deposited in the
    smoker's lungs.
   Arsenic (rat poison)
   Hydrogen Cyanide (gas chamber poison)

 Energy = the ability to work and cause
  change. (kinetic energy)
 Energy can be in many different
 Ex. Thermal (heat), radiant (light),

       electrical, mechanical, & chemical.
Free energy = the energy available to
  do work. (potential energy)
   Some animals use kinetic
    energy to catch and eat
    other animals.
   Some animals use kinetic
    energy to not get eaten
    by other animals.
   Sometimes kinetic
    energy is just fun. It
    feels good to run, or to
    be more technical, to
    convert potential energy
    stored in our cells into
    the kinetic energy of our
    Energy & Chemical
   Chemical reactions that NEED (absorb) energy are
    called ENDERGONIC.

   Ex. Photosynthesis
Energy & Chemical
   Chemical reactions that RELEASE
    energy are called EXERGONIC

   In both reactions, energy is needed to
    “get the ball rolling”. This is called
   Some chemicals actually reduce the
    amount of activation energy needed.
    These are called CATALYSTS.
   One group of catalysts are called
 Most organic compounds have clusters of
  atoms called functional groups.
 The functional group is the structural
  building block that determines the
  characteristics of the compound.
 One very important functional group is the
  hydroxyl group (-OH).
 Alcohol is an organic compound with a
  hydroxyl group attached to one of its
  carbons (making alcohol polar like water).
   Honors:
    Complete functional group work packet to
    fully understand the composition of the
    common function groups.

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