reactive
re-ac-tive
adjective
Readily undergoing a chemical reaction or interacting with other substances.
"Highly reactive elements can be dangerous."
adjective
Responding to events or situations rather than anticipating or preventing them.
"Their management style was too reactive, lacking foresight."
Thesaurus
Synonyms: labile, activated, excited, thermolabile, unstable, oxidizable, responsive, sensitive
Antonyms: unreactive