Dareen-celinta dheeraadka ah waa nooc fal-celin kiimikaad ah oo ay laba ama in ka badan oo unugyo ah isku darsamaan si ay u sameeyaan hal unug oo ka weyn. Dareen-celinta noocan ahi waxay caadi ahaan ka dhex dhacdaa molecules-ka leh curaarta aan dhergin, sida alkenes ama alkynes, waxayna ku lug leedahay ku-darka hal ama in ka badan oo atamka ama kooxo atamka ah oo labanlaaban ama saddex-laaban ee molecules-kan. Dareen-celinta isku-darka ah ayaa caadi ahaan loo isticmaalaa kimistariga dabiiciga ah si loo abuuro unugyo cusub ama wax looga beddelo kuwa jira.