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The next part of the lab deals with isomers. Isomers are molecules having the same molecular formula, but the atoms are arranged in a different manner, while still obeying the rules of bonding. There are different classifications for isomers. For example, structural isomers differ from one another in the order in which the atoms are bound to each other (connectivity is different). On the other hand, geometrical isomers have the same order of atoms, but the spatial arrangement of atoms is different (connectivity is the same). A common example of geometrical isomers is the cis and trans forms of double bonds:

** NOTE: Remember that molecules having single carbon-carbon bonds cannot have cis/trans isomers because there is free rotation about single bonds.

By building the models of various molecules during this lab, you will be able to better understand molecular symmetry and isomers. Building models is not difficult; however, the chemical principles involved are very important and you may find some surprises in how atoms can be fit together.

Finally, in Part 4, you will be applying your knowledge of VSEPR (Valence Shell Electron Pair Repulsion) Theory in order to determine the geometry of several different molecules. VSEPR theory is useful in helping to determine how atoms will orient themselves in molecules. Basically, the idea is that the arrangement adopted by a molecule will be the one in which the repulsions among the various electron domains are minimized. The two kinds of electron domains are bonding (electron pair shared by two atoms) and non-bonding (electron density centralized on one atom) pairs of electrons.

 

Experimental Procedure

For Parts 1&2: You and your lab partner are to work with one other lab group in preparing these models (no more than 3 - 4 students). Your TA will assign each group a certain set of molecules to make and answer questions pertaining to those molecules. Each group will then present their answers to the class. These models will need to be completed and answers determined within 30 minutes so that we can continue to Parts 3&4 as soon as possible.

For Parts 1-4, the work should be divided among the group members. Be sure to discuss the questions and answers among yourselves, but put your own conclusions on the Report Form.

 

1. Symmetry Elements

Using the Molecular Framework models, make models of the following compounds:

  1. CH 4
  2. CH 3 Cl
  3. CH 2 Cl 2
  4. CHCl 3
  5. CH 2 ClF
  6. CHBrClF
  7. BF 3
  8. BF 2 Cl
  9. PH 3
  10. PH 2 Cl

Choose a color to represent each atom. For example, make all C atoms black, all H atoms white, etc.

Once the models are created, look for symmetry elements that may be present. Ask yourselves the following questions:

  • Does the molecule contain a mirror plane ( σ ) ? In other words, is there a plane within the molecule which results in one half being a mirror image of the other half?
  • Does the molecule contain a two-fold rotation axis (C 2 ) ? Remember from the Introduction that the subscript indicates the degrees of rotation necessary to reach a configuration that is indistinguishable from the original one. In this case, the rotation will be 180 o .
  • Does the molecule contain any higher-order rotation axes?

Questions & Answers

how can chip be made from sand
Eke Reply
is this allso about nanoscale material
Almas
are nano particles real
Missy Reply
yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
Lale Reply
no can't
Lohitha
where is the latest information on a no technology how can I find it
William
currently
William
where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
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Source:  OpenStax, Honors chemistry lab fall. OpenStax CNX. Nov 15, 2007 Download for free at http://cnx.org/content/col10456/1.16
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