3.(a) Periodic Table, Isotope abundance

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3.(a) Periodic Table, Isotope abundance chapter
3 (b) Origin of Food
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A group of elements consists of all the elements
in any vertical column of periodic table. The
elements in each horizontal row of the periodic
table represent a period.
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The Periodic Table(see www.webelements.com)
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Isolation of Elements

• He from natural gas-looming shortage (escapes
  from the atmosphere)
• Ne, Ar, Kr, Xe come from fractional distillation
  of liquid air
• Radon (Ra) comes from radioactive decay of radium
• Halogens found as ions in sea salt, ie NaCl, KI
  etc.

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Evaporation of Sea water

• New Zealand Salt beds, sources of Cl, Br , I in
  salts

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The atomic weight
of an element is the average of the mass of all
of its isotopes, weighted for the abundance of
each.
If the
atomic weight of Cl 35.5
and Cl has two isotopes
35
37
Cl
Cl
17
17
Approximately how much of each isotope occurs in
natural abundance?
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Tough Question!

• Where to start?
• Any suggestions?
• If 50 of each isotope,
• atomic weight would be?

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Isotopes of Chlorine

• Let fraction of 35Clx, thus fraction of
  37Cl1-x
• So x(35) (1-x)37 35.5
• 35x 37 -37x 35.5
• -2x -1.5
• x.75
• Thus about 75 35Cl and 25 37Cl.

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Lifes Good things Come from Chemistry!
C H O Co La Te
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Food The Macronutrients

• Carbohydrates (4 calories/gram)
• Protein (4 calories /gram)
• Fats (9 calories/ gram)
• gt99 of calories come from these
• -------------------------------------------------
• Micronutrients Essential, but in much smaller
  amounts Vitamins, Minerals

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Where does our food come from?
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Origin of Carbohydrates Photosynthesis

• 6CO2 6H2O ? C6H12O6 6 O2
• Glucose (a sugar) is formed
• Reaction catalyzed by chlorophyll and requires
  sunlight
• Balanced Equation equal of C, H, O on LHS and
  RHS

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Biosynthesis of Carbohydrates

• Plants convert glucose to more complex sugars ie.
  cellulose, starch
• Plants fix nitrogen from soil and air (78
  N2, 20 O2, all others 2)
• Animals convert plants to protein and fats

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Biosynthesis of Fatty Acids

• Complex involve enzymes (catalysts) , ie Acetyl
  Coenzyme A.
• Fats are biosynthesized by sequential addition of
  2C units.
• Palmitic acid a C16 saturated fatty acid
  requires 8 Acetyl Co A units
• Plants make these in their seed

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Biosynthesis of Fats in Plants

• Rapeseed (Canola) source of a healthy mixture
  of unsaturated fatty acids

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Biosynthesis of Protein

• From amino acids
• Human body can biosynthesize some proteins (for
  muscle, hair, hormones)