Georgia State University
Georgia State University: Hyper Physics: Neptunium
Good information on neptunium, all nicely arranged.
Florida-Spectrum Environmental Services
Florida Spectrum: Chemical Fact Sheet: Neptunium
This site provides a fact sheet with information on the basic data and properties of Neptunium. It also includes some of its uses.
Chemicool
Chemicool: Neptunium
This Chemicool site offers excellent data tables with known information on Neptunium.
Royal Society of Chemistry
Chemical Society: Neptunium
Short summary of basic information on neptunium.
TED Talks
Ted: Ted Ed: Neptunium: Periodic Table of Videos
The team at Periodicvideos has created a TED-Ed Lesson for every element of the periodic table. We get a close-up look at neptunium during a visit to the National Nuclear Laboratory at Sellafield. [5:46]
Web Elements
Web Elements Periodic Table: Neptunium
WebElements provides a very good source of basic information on neptunium, including physical properties, isotopes and electron configuration.
Corrosion Source
Corrosion Source: Neptunium
Easy to follow information on the history, sources, properties and isotopes of neptunium.