Structural Isomers and Formulas

1. Convert between structural, line, and skeletal formulas.
2. Predict possible structural isomers associated with a molecular formula.

The Different Formulas

Structural Formula

Classic letters & lines. Doesn’t show true shape, only bonds between atoms.

Formulae for water:

Molecular:

Structural:

Formulae for octane:

Structural:

Molecular: (octane)

Line Formula

Does not involve lines. Basically a molecular formula, but gives more information about the structure.

Formulae for octane:

Line:

Molecular:

Skeletal Formula

Used specifically for organic chemistry; removes the clutter of s and s.

Formulae for octane:

Skeletal:

Molecular:

Isomers

Isomers are molecules with the same molecular formula, but different structures. There are two categories of isomers:

Structural Isomers

A structural isomer has the same number of atoms of each element (thus the same molecular formula), but the atoms are connected in different ways.

Stereoisomers

A stereoisomer has the same atoms connected in the same way, but in a different shape.

Identifying the (Structural) Isomers of a Molecular Formula