Hydrogen (H)
“The lightest and most abundant element in the universe — nine out of every ten atoms are hydrogen.”
How its electrons are arranged
Computed from the aufbau principle, with known real-world exceptions applied automatically.
Characteristics
- The lightest atom of all: one proton and one electron. Its electron configuration is 1s¹, and it sits in Period 1, Group 1.
- Burns in oxygen with an almost invisible pale-blue flame, producing pure water — the reaction that once destroyed the Hindenburg airship.
- Highly flammable and very reactive as an atom, but the H₂ molecule itself is quite stable; it takes heat or a catalyst to get it reacting.
- The most abundant element in the universe — the Sun fuses about 600 million tonnes of it into helium every second.
A colourless, odourless gas at room temperature. It exists as diatomic molecules (H₂) — two atoms joined in a pair — and is about fourteen times lighter than air, which is why it was once used to fill balloons.
Where you meet it
✦ Uses
- Making ammonia (NH₃) for fertilizer — the Haber process consumes hydrogen on a gigantic scale; Bangladesh’s fertilizer factories rely on the same chemistry.
- Hardening vegetable oils to make margarine and vanaspati ghee — hydrogen is bubbled through the oil with a nickel catalyst.
- Fuel for rockets and fuel-cell vehicles — burning it releases lots of energy while the only exhaust is water.
- Filling weather balloons and, historically, airships; also used in oxy-hydrogen torches for cutting and welding metals.
◍ Everyday examples
- Water — H₂O — is two-thirds hydrogen by atom count; every glass you drink is full of it.
- The Sun and other stars are giant balls of hydrogen plasma; the acids in a lab and in your stomach all owe their acidity to hydrogen ions.
- Sachet milk, mustard oil and petrol in a Bangladeshi kitchen or filling station are all hydrogen-rich compounds.
History & name
In 1766 the English scientist Henry Cavendish collected a strange “inflammable air” by dripping acid on metals, and showed that it burned to form water. Antoine Lavoisier later repeated the work, named the gas hydrogen — from the Greek hydor (water) and genes (forming) — and recognised it as a true element. Its connection to water made it a cornerstone of the chemical revolution.