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# hydrogen

noun (hydrogen — uncountable)

«hydrogen» in the English dictionary: everyday — its meanings, how the lessons use it, and examples, each with its tree on Mova.

## Everyday

The lightest of all chemical elements; a gas with no colour, smell or taste that burns easily. Its chemical symbol is H. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/H/hydrogen/#m1)

### In the lessons

In science: hydrogen is number 1 in the periodic table; it is the most common element in the universe; stars like the Sun get energy by turning hydrogen into helium. Water is H2O: two atoms of hydrogen and one of oxygen. Hydrogen is used as a clean fuel for some buses and rockets. Phrases: «hydrogen gas», «hydrogen fuel», «hydrogen and oxygen».

### Examples

- Water is made of hydrogen and oxygen. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/H/hydrogen/#x1)
- Hydrogen is the lightest gas there is. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/H/hydrogen/#x2)
- The Sun is mostly hydrogen. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/H/hydrogen/#x3)
- Some buses run on hydrogen fuel. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/H/hydrogen/#x4)
- Hydrogen burns with a squeaky pop in a test tube. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/H/hydrogen/#x5)
- Hydrogen's symbol is H. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/H/hydrogen/#x6)
- Old airships were filled with hydrogen, which is dangerous because it burns. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/H/hydrogen/#x7)

### Note

Uncountable. Symbol H, atomic number 1. Safety: hydrogen catches fire very easily — party balloons use helium instead, which does not burn. Hydrogen is a gas at room temperature.

## On Mova

- [Trees and pragmatics of «hydrogen» in the school dictionary](https://mova.elamur.ai/free/en/corpora/dictionaries/school/H/hydrogen/): every meaning and example parsed by Mova, with its dependency tree and frames.
- [«hydrogen» in the school dictionary](https://mova.elamur.ai/free/en/dictionaries/school/w/hydrogen.html) on Mova free.