Drawing Three Dimensional (3-D) Structures on Paper

A Brief Review of Line Structures

Line structures are the organic chemists shorthand for drawing chemical structures on paper.

Consider propane, a simple alkane with the molecular formula C3H8.

A beginner might draw an extended structure, showing all of the bonds an atoms in propane:

This is a useful, but not particularly accurate drawing of propane. (Note the lack of three dimensional information.) Extended structures of large molecules are also rather tedious to draw. Imagine drawing a molecule with 30 C's and 80 or 90 H's!

Thus, chemists have taken to using line structures for most drawing of structures. The line structure for propane looks like this:.

Obviously, this is much easier to draw but one needs to understand the "rules" used to draw this structure in order to "see" it as propane. Fortunetly, the rules are quite simple.

Rules for drawing line structures:

  • Each carbon is represented by the end of a line segment or the junction between a two line segments.
  • All hydrogens attached to carbons are NOT drawn.
  • All other atoms (heteroatoms and hydrogens attached to heteroatoms) are shown explicitly.
  • Look at a few more examples, in order to become familiar with line structures:

    What about stereochemical information or three dimensional information? Please go to the next page for this topic.



    Go to the Table of Contents



    Back to Organic Chemistry



    HOME