I have to build a model of a molecule and I was wondering how to determine its bond lenghts.
(It has C-H, C-O, C=O, C-N, C-C & C=C bonds.)
Also, will the lengths of all of one type of bond be the same throughout the molecule? Er...for example, if I found the length of a C-H bond, would every C-H bond be the same length in this molecule?
Bond lengths are not always the same for a particular bond. Most references give average bond lengths. Here is a good site that gives averages plus some specific lengths depending upon the environment.http://ww1.iucr.org/comm/cteach/pamphlets/15/node6.html
Bond angles are more important in building molecular models than bond lengths. You can get approximate bond lengths by looking up the covalent radius of both elements linked and add them up. Double and triple bonds are shorter than single bonds. Some of the bonds you need are here:
http://www.science.uwaterloo.ca/~cchieh/cact/c120/bondel.html
To determine the bond lengths in a molecule, you typically need access to the molecular structure, which includes the positions of atoms in 3D space. There are a few ways you can go about determining bond lengths:
1. Experimental methods: Techniques such as X-ray crystallography or spectroscopy (e.g., infrared or Raman spectroscopy) can provide information about bond lengths in a molecule. X-ray crystallography involves analyzing the diffraction pattern produced by a crystal to determine the positions of atoms, while spectroscopy measures the interaction of molecules with light waves.
2. Computational methods: Tools like molecular modeling software or quantum chemistry calculations can also provide estimates of bond lengths. These methods use mathematical models to simulate molecular structures and properties. They can be useful when experimental data is not available or to validate experimental results.
Regarding your second question, the lengths of bonds between the same atoms can vary due to several factors. Factors like bond order, bond strength, and the surrounding chemical environment can influence bond lengths. In the case of C-H, C-O, C=O, C-N, C-C, and C=C bonds, the bond lengths might vary depending on the specific functional groups attached to the carbon atoms and the molecular conformation.
It's important to note that while there might be general trends or average values for certain bond lengths, the exact bond lengths in a molecule can vary depending on its specific structure and environment. So, if you measure one C-H bond length in a molecule, it doesn't necessarily mean that all C-H bonds in that molecule will have the exact same length.