unimolecular

7.3

A chemical reaction that involves only one molecule

adjective
/ˌjuːnɪˈmoʊkjələr/

Specialized

: unimolecular

So the first reaction is called unimolecular because there's only one thing reacting.

Examples

In a unimolecular reaction, a single molecule undergoes a transformation without any direct interaction with other molecules.
Chemists often study unimolecular processes to understand how a single molecule can initiate a reaction.
One example of a unimolecular reaction is the decomposition of hydrogen peroxide into water and oxygen.

Synonyms

monomolecular

vsunimolecular

Specialized

9.2

A chemical reaction that depends on how much one substance is present

is broader, meaning a single molecule is involved in any part of a reaction

Antonyms

bimolecular

Specialized

8.4

Involving two molecules in a chemical reaction

How Many Molecules

trimolecular

Specialized

8.6

bimolecular

Specialized

8.4

unimolecular

Specialized

7.3

Surface Forms

unimolecular positive

Morphology

unimolecular = molecular (transparent) = uni + molecular

The adjective is built by prefixing 'uni-' (one) to 'molecular', yielding the straightforward meaning 'involving a single molecule'.

Etymology

Unimolecular combines uni- 'one' and molecule 'tiny particle', like the uni- in unicycle which means 'one'. So a unimolecular reaction involves just a single molecule doing the work.