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Hydrogen was recognized as a distinct element by Henry Cavendish in 1776. It is one of the most abundant substances in the Universe.
This category contains sites about the element Hydrogen.

All sites submitted to this category should be of interest to and appropriate for children under the age of 18. Please remember that no site is guaranteed placement in the Kids and Teens section of the Open Directory.

Sites that are primarily designed to sell products or services will not be listed in any branch of Kids and Teens.