# ionization

/ˌaɪənəˈzeɪʃən/ (US) · CEFR C1 · Noun

Source: https://englishreference.com/word/ionization
Updated: 2026-08-15

## Definition

the process where an atom or molecule gains or loses electrons to get an electric charge. This often happens because of heat, electricity, or chemicals.

For teachers: the process by which an atom or molecule acquires a negative or positive charge by gaining or losing electrons. Often occurs through high-energy collisions or exposure to electromagnetic radiation.

## Examples

- The ionization of gas creates a glowing effect in neon signs.
- In the upper atmosphere, solar radiation causes the ionization of air molecules, creating the ionosphere.
- Mass spectrometry relies on the efficient ionization of sample molecules, allowing them to be accelerated and separated by their mass-to-charge ratio within a magnetic field.

## Usage notes

- Uncountable when referring to the general physical process; can be countable in specific technical descriptions of different methods.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.