hydrogen

hydrogen — noun

1. the simplest known element, which exists as a colourless gas and weighs less tha

1.nounB1
Definition

the simplest known element, which exists as a colourless gas and weighs less than any other substance; when you burn it together with oxygen, water is created.

Example

The bus company is testing hydrogen fuel cells as a cleaner alternative to diesel engines.

collocation: hydrogen fuel cells

Adisa watched the hydrogen-filled balloon drift up toward the ceiling of the laboratory.

hydrogen-filled [noun] as a compound adjective

Common collocations
  • hydrogen fuel
  • hydrogen atom
  • hydrogen molecule
  • hydrogen bond
  • hydrogen-powered
  • liquid hydrogen
  • hydrogen production

Grammar Patterns

hydrogen + noun (hydrogen fuel, hydrogen atom, hydrogen bond)

Usage Note

In everyday conversation, hydrogen often appears in compound nouns such as hydrogen fuel, hydrogen power, and hydrogen bomb. In scientific writing, it is commonly treated as an uncountable noun, though the plural hydrogens may be used informally to mean 'hydrogen atoms.'

Common Mistakes

Water is two hydrogen and one oxygen.
Water is made of two hydrogen atoms and one oxygen atom.
You need to add 'atom(s)' when describing the molecular composition of a compound.
Helium is very flammable, like hydrogen.
Unlike hydrogen, helium does not burn.
Hydrogen is highly flammable; helium is a non-flammable noble gas. Learners often confuse the two because both are used in balloons.

Word family

  • hydrogenate
    verbC1
  • hydrogenation
    nounC2
  • hydride
    nounC2

Synonym discussion

Sense: noun/1

Hydrogen, helium, oxygen, and carbon are all common chemical elements, but each has very different properties. Hydrogen (atomic number 1) is the lightest element and is highly flammable — it was famously used in airships such as the Hindenburg. Helium (atomic number 2) is also very light and is frequently confused with hydrogen because both are colourless gases, but helium is non-flammable and safe for party balloons. Oxygen is the gas we breathe; unlike hydrogen, it supports combustion rather than burning itself. Carbon is a solid at room temperature and is the backbone of organic chemistry. A memorable distinction: hydrogen + oxygen = water (H₂O); helium keeps balloons afloat without any risk of fire.

hydrogen ↗heliumoxygen ↗carbon ↗

Common collocations

Nouns

Phrases

  • hydrogen and oxygen
  • hydrogen-powered vehicle
  • liquid hydrogen

Prepositions

  • of hydrogen
  • in hydrogen

Etymology

GreekFrenchEnglish

Coined in the late 18th century by the French chemist Antoine Lavoisier from the Greek words hydor (water) and gennan (to produce), literally meaning 'water-former' — because burning hydrogen produces water. The English word is adapted from the French hydrogène.