eg: Butyl alcohol (1) and isobutyl alcohol (2) are constitutional isomers containing the same functional groups, namely the alcohol group.
They differ from each other in the connectivity of the carbon skeleton.
Thus, 1 and 2 are skeletal isomers.
OCHEMPAL IS NOW IN THE FORM OF A BOOK*
Title: The Elements of Organic Chemistry
Subtitle: A Compendium of Terminology, Definitions, and Concepts for the Beginner.
Available at the publisher’s website here: http://linusbooks.com/?wpsc-product=the-elements-of-organic-chemistry
* The book contains everything on OChemPal except a few biochemical terms and the Mastery Check feature.