Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Examples of typical elementary molecules. On the left side, two different elementary molecules, A and B, are displayed with three sites, a, b and c, which are represented by the circles. The attached squares on the right symbolize a modification of the site, b. In this example, no further information about the kind of modification is given.
