A portal or gateway site is the best place to begin research. These sites, which are intended to serve as "jumping off" points, will lead the researcher to a variety of useful sources that have been selected because of their relevance or quality. A portal site may include thousands of links on a wide range of topics, or may be very specific in scope and point to a small number of resources.

Portal sites may allow keyword searching, provide topical, hierarchical browsing (drilling down) or both search and browse capabilities. Another useful starting point for research is the search engine, particularly those that are subject-specific.
intute: science, engineering & technology
http://www.intute.ac.uk/sciences/
Intute organizes over 18,000 Web resources for education and research and makes them searchable by keywords or browsing. These resources are "selected and evaluated by a network of subject specialists."
E-Print Archive
http://arXiv.org/
Started in Aug 1991, the E-Print Archive (arXiv.org) is a fully automated electronic archive and distribution server for research papers. Covered areas include physics and related disciplines, mathematics, nonlinear sciences, computational linguistics, and neuroscience. Search by keyword or browse by topical area.
General Chemistry Online
http://antoine.frostburg.edu/chem/senese/101/index.shtml
This gateway site includes a searchable database of over 800 common compounds as well as a database of chemistry Web resources, a glossary, exam helpers and more.
Mathematical Atlas
http://www.math-atlas.org/
This gateway to math resources provides short articles with pointers to further information (both print and online) on number theory, algebra, geometry, topology, analysis, differential equations, applications, probability and statistics and history of mathematics. Each section also contains frequently asked questions and answers.
Scirus
http://www.scirus.com
Claims to be the most comprehensive science-specific search engine available on the Internet. Finds peer-reviewed articles, Web sites, and non-text files. Provides links to free as well as fee-based information.
AcademicInfo
http://www.academicinfo.us/
A listing of topics leading to scholarly Web sites suitable for research at the high school and college level. Browse by topics presented or use the keyword search function to find Web sites on a specific topic. Within each topical listing is a sub-category of portals and general resources. Web sites are selected because of their usefulness to students, educators and researchers.
The Internet Public Library Subject Collections (IPL)
http://www.ipl.org/div/subject/
Core internet resources are arranged by discipline and then by more specific subject area. An option is also available to find associations or serials related to the subject. These sites have been selected and organized by librarians. A link to pathfinders on very specific topics is also available.
Search Engine Guide
http://www.searchengineguide.com/
This guide indexes over 3,000 directories and search engines. Organized by category and searchable by keyword.

Use the glossary to search the term lithium on the General Chemistry Online site. What is its atomic weight?
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