Different ways of representing molecules

 

1) Chemical formula. It shows the types of atoms in the molecule, and, using subscripts, it shows how many of each type of atom is present.

The Chemical formula of butane is C4H10.

 

2) The structural formula of a molecule shows the symbol for every atom, and it shows every bond.

 picstruc1.gif

 

3) The condensed structure of a molecule shows the symbol of every central atom and of each ligand or set of ligands bonded to a central atom. Some bonds can be shown:  

CH3CH2CH2CH3                                The condensed structure of butane

 picstruc6sk2.gif

 

4) The line structure of a molecule shows the carbon backbone such that every apex represents a -CH2-

picstruc4sk2.gif

 

If an interior double bond is present the apex represents a -HC=

picstruc3sk2.gif                         

  

If an interior triple bond is present:

picstruc5sk2.gif

 

 

For terminal multiple bonds:

picstruc7sk2.gif

 

 

In line structures, bonds to heteroatoms are shown:

structures7a.gif

(A heteroatom is an atom other than carbon or hydrogen)

Exercises:

For the following exercises, if you are not able to do the 3D optimization and conversion from 2D to 3D using ChemSketch do not be alarmed, during the lab period, you will be shown how to do this.

 

1) A propane molecule contains three carbon atoms, and eight hydrogen atoms. On a sheet of paper, write the chemical formula, condensed structure, structural formula, and line structure of propane. With your model kit, build the ball and stick model of propane. Check your answers against the Hot Spot Activity below:

  

 

2) A cyclohexane molecule contains six carbon atoms, and twelve hydrogen atoms. On a sheet of paper, write the chemical formula, condensed structure, structural formula, and line structure of cyclohexane. Check your answers against the Hot Spot Activity below:

 

  

 

3) With your model kit, build the ball and stick model of cyclohexane and/or using ChemSketch's ACD/labs 3D viewer draw cyclohexane in 2D, then, 3D optimize it, and copy it to the "ACD/labs> 3D viewer", convert it to its ball and stick model. Check your answer against the animated image in the Hot Spot Activity below:

 

  

 

 

4) Using ChemSketch's ACD/labs 3D viewer draw cyclohexane in 2D, then, 3D optimize it, and copy it to the "ACD/labs> 3D viewer", convert it to its spacefill model. Check your answer against the animated image in the Hot Spot Activity below:

  

 

5) A benzene molecule contains six carbon atoms in a closed ring, it has 3 carbon-carbon double bonds and six hydrogen atoms. Using ChemSketch or on a sheet of paper, write the chemical formula, condensed structure, structural formula, and line structure of benzene. Check your answers against the Hot Spot Activity below:

  

 

6) With your model kit, build the ball and stick model of benzene and/or using ChemSketch's ACD/labs 3D viewer draw benzene in 2D, then, 3D optimize it, and copy it to the "ACD/labs> 3D viewer", convert it to its ball and stick model. Check your answer against the animated image in the Hot Spot Activity below:

  

7) With your model kit, build the ball and stick model of benzene (use two bowed bonds to make each double bond) and/or using ChemSketch's ACD/labs 3D viewer draw benzene in 2D, then, 3D optimize it, and copy it to the "ACD/labs> 3D viewer", convert it to its spacefill model. Check your answer against the animated image in the Hot Spot Activity below:

  

 

8) A molecule of 3-aminoprop-2-enal contains three carbon atoms connected to one another in a chain. The first carbon in the chain is also double bonded to an oxygen atom and that carbon atom is also bonded to a hydrogen. The second carbon in the chain is double bonded to the third carbon in the chain. The second carbon is also bonded to a hydrogen. The third carbon in the chain is bonded to a hydrogen and to an amino group (-NH2). Using ChemSketch or on a sheet of paper, write the chemical formula, condensed structure, structural formula, and line structure of 3-aminoprop-2-enal. Check your answers against the Hot Spot Activity below:

  

 

9) With your model kit, build the ball and stick model of 3-aminoprop-2-enal (use two bowed bonds to make each double bond) and/or using ChemSketch's ACD/labs 3D viewer draw the molecule in 2D, then, 3D optimize it, and copy it to the "ACD/labs> 3D viewer", convert it to its ball and stick model. Check your answer against the animated image in the Hot Spot Activity below:

  

 

10) Using ChemSketch's ACD/labs 3D viewer draw the molecule 3-aminoprop-2-enal (use two bowed bonds to make each double bond) and/or in 2D, then, 3D optimize it, and copy it to the "ACD/labs> 3D viewer" convert it to its spacefill model. Check your answer against the animated image in the Hot Spot Activity below: