Representations

We don’t usually use molecular formulas to refer to organic compounds because they give so little information. Instead, we use one of the following representations:

expanded molecular formula

a large molecular formula where each individual carbon is shown and is bonded to its adjacent symbols; brackets indicate side branches; for example, the EMF of 2,2-dimethylbutane is CH₃C(CH₃)₂CH₂CH₃

structural model

a three-dimensional model, either the ball and stick model or the space-filling model; see page 11 of the textbook for examples

complete structural diagram

a two-dimensional representation of the compound that shows every atom and the bond lines between them

condensed structural diagram

like complete diagrams, but hydrogen atoms don’t have to be shown individually: write CH₃ instead of C with —H three times

line structural diagram

the most compact representation; there is an implied carbon atom at any point where the line ends or bends (vertices and termini), and hydrogen atoms are inferred