El hidrógeno se representa en la tabla periódica por el símbolo H y tiene el número atómico 1. En condiciones normales de presión y temperatura, es un gas diatómico (H2) incoloro, inodoro, insípido, no metálico y altamente inflamable. Con una masa atómica de 1,00794(7) u, el hidrógeno es el elemento químico más ligero y es, también, el elemento más abundante, constituyendo aproximadamente el 75% de la materia del universo.
Hidrógeno en la Wikipedia.

Primer vídeo de la tabla periódica dedicado al hidrógeno, con subtitulos en español.

Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H.
At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H2. With an atomic weight of 1.00794, hydrogen is the lightest element.
Hydrogen is the most abundant of the chemical elements, constituting roughly 75% of the universe's elemental mass.Stars in the main sequence are mainly composed of hydrogen in its plasma state. Elemental hydrogen is relatively rare on Earth, and is industrially produced from hydrocarbons such as methane, after which most elemental hydrogen is used "captively" (meaning locally at the production site), with the largest markets about equally divided between fossil fuel upgrading (e.g., hydrocracking) and ammonia production (mostly for the fertilizer market).
Hydrogen may be produced from water using the process of electrolysis, but this process is presently significantly more expensive commercially than hydrogen production from natural gas.