Representations in 2D of hydrocarbons

There are numerous ways to represent the elements and structure of a chemical compound. Below you will find some of the most common types used for organic compounds, each with different strengths and weaknesses. Be aware that variations of each type are not uncommon, usually when certain molecule groups or bonds are to be emphazised.

Molecular formula

The molecular formula gives the total number of each element present in the compound. It does not reveal any information about the structural arrangement of the elements though.

Displayed formula

The displayed formula writes out the entire structure of the compound in detail, showing all elements and bonds. It can quickly become hard to read though for larger and more branched compounds.

Partially condensed formula

A representation similar to the displayed formula, but where all bonds to hydrogen are hidden, or "condensed".

Condensed formula

In the condensed formula, the structure is written as an equation based on the carbon backbone, with all bonds hidden and side groups grouped together. Sometimes, double/triple bonds are explicitly shown for clarity.

Skeletal formula

In the skeletal formula, all carbons and hydrogens are hidden. Carbons are implied at the vertices (corners and end points) of the drawn structure, and number of hydrogens inferred by always assuming four bonds for each carbon. When going beyond hydrocarbons and including functional groups, hydrogens will usually be explicitly drawn when they are part of a functional group.

Figure 1. The hydrocarbon 2-methyl-but-2-ene shown in various types of formula and 2D representations.