Hydrogen
Definition and meaning of Hydrogen in chemistry.
Hydrogen is the chemical element with atomic number 1 and symbol H, the lightest and most abundant element in the universe, existing under standard conditions as the colorless, odorless, highly flammable diatomic gas H2.
In more detail
Each hydrogen atom has one proton and one electron, giving the ground-state configuration 1s1. This lone electron lets hydrogen form covalent bonds (as in H2 or H2O), lose its electron to become a bare proton (H+, central to acid-base chemistry), or gain an electron to form the hydride ion (H-). Hydrogen has three natural isotopes: protium (no neutrons, over 99.98% of natural hydrogen), deuterium (one neutron), and radioactive tritium (two neutrons). Industrially, hydrogen is essential to the Haber-Bosch process for ammonia synthesis, petroleum refining, and fat hydrogenation, and it is gaining use as a clean-burning fuel and energy carrier.
Key facts
| Symbol | H |
|---|---|
| Atomic Number | 1 |
| Molecular Formula | H2 (diatomic form) |
| Field | General Chemistry |
Hydrogen gas is combined with nitrogen in the Haber-Bosch process, N2(g) + 3H2(g) -> 2NH3(g), to manufacture ammonia for fertilizer on an industrial scale.
Frequently asked questions
Why is hydrogen sometimes shown separately from the other groups on the periodic table?
Its single 1s1 electron gives it properties that only partly resemble the alkali metals (group 1, which it technically heads) and, in some respects, the halogens, so many periodic tables set it apart to reflect this dual character.
Is hydrogen gas dangerous?
Pure H2 is nontoxic but highly flammable and forms explosive mixtures with air across a wide concentration range; it burns with a nearly invisible pale blue flame, producing water: 2H2 + O2 -> 2H2O.