Reaction
ree-AK-shuhn
/riˈækʃən/
A process that involves rearrangement of the molecular or ionic structure of a substance, as opposed to a change in physical form or a nuclear reaction; also, a response to an action or stimulus.
In chemistry, it's a specific transformation. In general use, it's any response, which can be emotional or physical.
The story behind the word. The word 'reaction' comes from the Latin 're-' meaning 'back' or 'again,' and 'agere,' meaning 'to do' or 'to act.' So, it literally means 'to act back' or 'to act in response.' This origin perfectly captures both its general sense of a response to a stimulus and its specific chemical meaning, where substances 'act back' on each other to form new ones.
Word relationships
- response: More general term for an answer or reply, often to a stimulus.
- interaction: Mutual action or influence, often implies two things acting on each other.
- transformation: A more general term for a change in form or nature.
- inaction: Lack of action or response.
- stimulus: That which provokes a reaction.
Commonly confused with
- Process: A reaction is a specific type of chemical process involving molecular rearrangement; 'process' is a broader term for a series of actions or steps.
Word family
- react (verb): To act in response to something; to undergo a chemical change.
- reactive (adjective): Showing a response to a stimulus; readily undergoing a chemical reaction.
Collocations
- chemical reaction
- allergic reaction
- chain reaction
- adverse reaction
- knee-jerk reaction
Idioms & expressions
- chain reaction
- knee-jerk reaction
Example sentences
- "The acid-base reaction produced salt and water, along with a noticeable release of heat." In a chemical context.
- "Her immediate reaction to the news was shock, followed by a wave of relief." Referring to a response.
- "Newton's third law states that for every action, there is an equal and opposite reaction." From a scientific principle.
Memory hook
Think of 'RE-ACTION' as an 'ACTION' that happens 'RE-sponding' to something else. RE-ACTION: RE-sponding action
When not to use
Do not use 'reaction' to describe a physical change (like melting ice) unless it's part of a broader chemical process.
Fun facts
- The concept of chemical reactions is fundamental to understanding all biological processes, from photosynthesis to metabolism.
- Some reactions, like nuclear reactions, involve changes within the atom's nucleus, not just its electron structure.
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