University of Illinois
University of Illinois: Illinois State Water Survey: Simplified Nitrogen Cycle
A semi-technical description of the nitrogen cycle. Contains a link to an abridged version of the page along with a list of further resources on the topic.
Shodor Education Foundation
Shodor: Acid Base Chemistry
This Shodor Education Foundation page has a nice look at the major theories of acids and bases in less than one page. There are very simple defintions.
Chemicool
Chemicool: Nitrogen
This site from Chemicool provides a set of data tables summarizing basic chemical and physical properties of nitrogen.
ClassFlow
Class Flow: Nitrogen
[Free Registration/Login Required] In this flipchart, students are introduced to the element nitrogen, its gaseous state, atomic structure, and how it combines with hydrogen to form ammonia.