Hydrogen Hydrogen Hydrogen is a chemical element with symbol H and atomic number 1. With a standard atomic weight of , hydrogen is the lightest element on the periodic table. Its monatomic form (H) is the most abundant chemical substance in the Universe, constituting roughly 75% of all baryonic mass. Non-remnant stars are mainly composed of hydrogen in the plasma state. The most common isotope of hydrogen, termed "protium" (name rarely used, symbol H), has one proton and no neutrons. The universal emergence of atomic hydrogen first occurred during the recombination epoch. At standard temperature and pressure, hydrogen is a colorless,
The Periodic Table of Science Fiction The Periodic Table of Science Fiction The Periodic Table of Science Fiction is a collection of 118 very short stories by science fiction author Michael Swanwick. Each story is named after an element in the periodic table, including the then-undiscovered element 117. The stories were commissioned to run on Eileen Gunn's The Infinite Matrix but were published in the Sci Fiction section of SciFi.com, between 2001 and 2003. The stories were published as they were written, about which Swanwick said, "It made the sequence into a kind of performance art, something akin to being a trapeze artist, which is a