reactive

This term often carries a negative connotation in professional or psychological settings. It describes a state of waiting for something to happen and then responding to it, which suggests a lack of foresight, leadership, or emotional control. A reactive person is seen as being driven by external events rather than their own internal goals.

In a scientific or technical context, the word is neutral and descriptive. It refers to the physical property of a material to undergo a chemical change. Here, the feeling is one of volatility or potential energy, describing how a substance interacts with its environment on a molecular level.