Where to find information about elements on the periodic table.
Books and encyclopedias are great places to find background information about a topic. For advanced, current research, use articles from academic journals.
Chemistry of the Elements by 
Articles from academic journals are the best place to find new information about a topic. Articles tend to be very detailed and advanced, so it's best to read background information (books, encyclopedias, etc.) before diving into current research.
These websites contain credible information about elements on the periodic table.