Category: Nonmetal
Atomic Number: 1
Period: 1 | Group: 1
Block: s-block
The simplest atom there is — one proton, one electron — and about 90% of every atom in the universe.
| Property | Value |
|---|---|
| Phase at STP | Gas |
| Density | 0.00008988 g/cm³ |
| Melting Point | 14.01 K (-259.14 °C) |
| Boiling Point | 20.28 K (-252.87 °C) |
| Heat Capacity | N/A |
| Property | Value |
|---|---|
| Atomic Mass | 1.0080 u |
| Electronegativity (Pauling) | 2.20 |
| Oxidation States | -1, +1 |
| Electron Configuration | 1s¹ |
| Discovered By | Henry Cavendish |
|---|---|
| Discovery Year | 1766 |
| Named After | Greek hydro + genes, "water-former" |
| ISOTOPE | Neutrons | Natural Abundance | Half-life | Decay Mode |
|---|---|---|---|---|
| H-1 | 0 | 99.9855% | Stable | - |
| H-2 | 1 | 0.0145% | Stable | - |
| H-3 | 2 | - | 12.32 yrs | β⁻ |
Data: IAEA Nuclear Data Section, LiveChart of Nuclides, ground-state evaluations, retrieved October 10, 2026. Abundance is the share of atoms in the natural element; a dash means the isotope has no standard natural abundance.
Ammonia, refining and methanol
Most hydrogen is used where it is made, in chemical plants and oil refineries. The largest uses are making ammonia for fertilizers by the Haber-Bosch process (N₂ + 3H₂ → 2NH₃), refining crude oil by hydrocracking and by removing sulfur from fuels, and making methanol. According to the International Energy Agency, world demand is close to 100 million tonnes a year, and almost all of it is still produced from fossil fuels.
Other industrial uses
Food: hydrogenation with a nickel catalyst turns liquid vegetable oils into solid fats.
Metals and glass: hydrogen atmospheres prevent oxidation in metal heat treatment and float glass production, and hydrogen can reduce metal ores to metal; pilot plants use it to make iron without coke.
Electronics: very pure hydrogen is a process gas in semiconductor manufacturing.
Energy and spaceflight
Rocket fuel: Liquid hydrogen fuels NASA's Space Launch System; SpaceX Starship uses liquid methane and liquid oxygen.
Fuel cells: fuel cells combine hydrogen with oxygen from the air to make electricity, with water as the only exhaust. They power a small number of cars, buses, trucks and forklifts.
Energy storage: hydrogen made by splitting water with renewable electricity (electrolysis) can store energy for industry or power generation, though this is still a small share of supply.
Water, natural gas and other hydrocarbons; produced mainly by steam reforming of natural gas
| Earth's Crust | 0.0014000000 ppm |
|---|---|
| Universe | 0.7500000000 % |