CHE106: C h e m i c a l S c i e n c e C o n c e p t s
Periodic Table and Name Organic Models Partners
Date
Objectives
o To describe various regions of the periodic table o To identify the elements given the atomic number, group numbers and period o Build and analyze models of simple and complex organic compounds
1. Complete the following table:
Element Symbol Atomic No. Atomic Weight Magnesium (a priming agent in explosives) Mercury, (a contaminate found in some seafood ) Lead (Component of gunshot residue) Sodium (component in fingerprint residue) Boron (provides shock resistance in glass) Plutonium (an artificial radioactive element1)
Fill in the blanks.
a. The least reactive element in Group I is ______.
b. Non-metals are found on the ______side of the periodic table.
c. A substance that is described as an ionic compounds usually contains a
______and a ______.
d. Element number 34 is a ______metal.
1An artificial element does not have an atomic weight, which is the average mass of the isotopes that occur in nature. It is usual to give the mass number of the most common isotope, in parentheses. 106: C h e m i c a l S c i e n c e C o n c e p t s
2. Complete the following table:
Atomic Name of Element Symbol Number 79
82
33
29
56
6
.
3. Give the family (group) and period that the following elements. Use Roman numerals, for example, VI-B.
Group Period Element Aluminum
Strontium
Arsenic
Potassium
Bismuth
.
2 106: C h e m i c a l S c i e n c e C o n c e p t s
4. Circle the symbol for any element that is a metal.
He Th Ar U
Ac Se Zr Ba
5. Circle the symbol for any element that is a transition element; draw a triangle around the symbol for any element that is an inner transition element.
Na Np Fe Tl
Pm P V Au
6. Indicate the type of bonding (covalent, ionic, or metallic) to be expected between atoms of each pair:
Ba and Cl
Fe and Cr
P and I
Mo and F
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Organic Models
Working with molecular models is extremely helpful in visualizing organic compounds. The arrangement of atoms in space is quite different from the way we draw them. This spatial arrangement turns out to be vital (literally); atoms may have the same sequence, but not the same biological activity. Large molecules have many possible spatial arrangements. Do not regard this exercise as child’s play; Watson and Crick won a Nobel Prize for working out the structure of DNA using models. Children enjoy it too.
Experimental: The set of model atoms we are using has colored wooden balls, which are connected with pegs and springs. At the end of the period, make sure all bonds are removed and the model kit is in the same condition that you found it. A bin of extra balls is available so you can adjust the numbers of each. Pliers are available to remove pegs. Use the appropriate color ball for the elements when constructing your models.
Carbon: black Bromine: orange Hydrogen: yellow Chlorine: green Oxygen: red Fluorine: violet Nitrogen: blue
Because hydrogen atoms are so small, use shorter pegs for all bonds to H atoms (yellow balls). Long pegs are used for all other single bonds. Two springs are used for a double bond, and three springs for a triple bond. Do not use a single spring to represent a single bond.
NOTE: Carbon always forms four bonds, counting double and triple bonds as two and three bonds each; hydrogen forms one bond; oxygen forms two bonds and nitrogen forms three bonds. Build the following compounds and have your instructor initial each section of your report.
1. Methane – Use short pegs to connect four atoms of H (yellow) to an atom of C (black). The actual shape of a carbon compound with only single bonds is called tetrahedral. We represent the structural formula on paper as if it were flat,
4 106: C h e m i c a l S c i e n c e C o n c e p t s square planar, with 90° angles because it is easy and convenient to draw the compounds this way.
H H
C H C H H H H H
Tetrahedral Square planar
Ethanol and 2-propanol are the alcohols used in the GC experiment. Although the compounds contain the same functional group, their biological properties are quite different. Ethanol is found in alcoholic beverages whereas 2-propanol is rubbing alcohol and is quite poisonous if ingested.
2. Ethanol – Build a model of ethanol CH3CH2OH. Connect the carbon atoms with a long peg. Draw the structural formula (not a picture of your model) of ethanol in the space provided.
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OH
3. 2-Propanol – Build a model of 2-propanol, CH3CHCH3.
Notice that the carbon chain is not straight, although we draw it as straight for clarity and the “OH” is connected to the second carbon of the chain. Draw the structural formula.
Show your models to your instructor before you dismantle them.
Many organic and biochemical compounds possess the property of “handedness” and are called stereisomers. Compounds containing a carbon atom bonded to four different elements are “handed” and are easily recognized.The fact that “handed” molecules are nonsuperimposable mirror images gives many of the these compounds special properties. All naturally occurring carbohydrates, proteins and enzymes are handed. Many drugs such as ibuprofen, LSD, methamphetamine and antibiotics are “handed” as well.
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4. Stereisomers – Build models of the two compounds that are shown below paying particular attention to the bond orientation. Are the compounds nonsuperimposable? ______
F F
C C H H Br Br Cl Cl
a. Replace a bromine atom (Br-orange ball)with a hydrogen atom (yellow ball) in both of your structures. Are the compounds nonsuperimposable? ______Explain your answer.
Show your models to your instructor for credit.
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5. Build one compound from the list below (a- f) and show it to your instructor for credit. a. Aspartame (also known as NutraSweet) is a synthetic dipeptide that is 200 times sweeter than sucrose (table sugar).
O H O NH2 H C C N C HO C C H2 OH H O H2C
b. d-Methamphetamine is a stimulant and resembles amphetamine, the active ingredient in prescription diet pills.The d-isomer, shown below has the stimulant effect whereas it mirror image does not.
CH3
C H C H2N H2
c. Splenda(sucralose) is an artificial sweetener that is 60,000 times sweeter than sucrose
CH2OH
Cl O
OH
O OH
OH
O OH ClH2C
8 106: C h e m i c a l S c i e n c e C o n c e p t s d. TNT= 2,4,6-trinitrotoluene is considered a high explosive used mostly in military and commercial blasting.
CH3
O2N NO2
NO2
e. Procaine also known as Novacain is a local anesthetic.
O
C OCH2CH2N(CH2CH3)2 NH2 O
f. Luminol gives off a photon of light in the presence of hydrogen peroxide, iron and blood. It is used to detect traces of blood even after the area has been cleaned.
NH2 O
NH
NH
O
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