the.com/reactivity
How violently a thing answers when reality pokes it.
means The tendency of a substance or system to undergo chemical change, often measured by how eagerly and energetically it reacts.
from From Latin re- (back, again) plus agere (to drive, act) — literally the capacity to act back when acted upon, coined as chemistry matured in the 1800s.
Periodic trendMetals get fiercer down a group, nonmetals up.
Cesium dramaIt can explode on contact with plain water.
Noble snubNoble gases barely react with anything, ever.
Code meaningIn programming, UIs that update themselves on data change.