How to Draw Bond Line Structures
Bond line drawings are a more efficient way to draw molecular structures than what we have seen to this point. They vastly simplify your work later in the semester because they are so quick and easy to draw. Here are the key fundamentals covering how to draw bond line structures:
• Carbon atoms are not explicitly drawn. Instead, it is assumed that a carbon atom is at the beginning and the end of a chain, as well as each change in angle.
• Hydrogen atoms are “implied” (meaning not explicitly drawn) on all carbon atoms. All other atoms must have their hydrogens explicitly drawn out. For example, all hydrogens on oxygen and nitrogen must be clearly shown.
• Using bond line drawings, we can now see that atoms typically arrange themselves in a “zig-zag” pattern, which minimizes the interactions between individual atoms. But remember, there is free rotation around single bonds, so the molecule can freely change conformations.
Despite the many different conformations in which a molecule might be able to orient itself, the “zig-zag” pattern is the preferred conformation as it is the most stable.
Free rotation can only occur in single bonds. This rule does not apply to double bonds as they are essentially locked in place due to the pi bond.
That being said, note that the single bonds in this molecule do still have free rotation.
In summary, bond line molecular structures are quicker and easier to draw. They also give us information about the conformation of the molecule, which we didn’t have with previous methods to depict molecules.
Hopefully you learned how to draw bond line structures from this section!