Reactive

Mary's realisation that she was gay plunged her into a reactive depression.

We'd much rather be proactive than reactive.

We have been reticent, or maybe just slow, or maybe we’ve denied the changes that are going on. And so we’ve been slow to react to them. We haven’t been proactive. We’ve been reactive.

Retroactive jealousy is more toxic than reactive jealousy.

Are humans good at reactive aggression?

NASA scientists said on Tuesday that the Phoenix Mars Lander has detected the apparent presence of a chemically reactive salt called perchlorate in the Martian soil. Perchlorate is a toxic material that's used in rocket fuel, but the scientists said its presence doesn't lessen the possibility that Mars has or once had some kind of life on it.

This is an ideal application for argon gas, whose inertness gives it a huge safety advantage over more reactive gases.

francium is the most reactive of the alkali metals.