Property to react, chemically, or in any other sense. It can also be defined as sensory stimulation or unusual interest in aspects of the environment, such as indifference to heat or cold, as well as giving adverse responses to specific sounds or textures, also having an exacerbated sense of smell or touch. Reactivity is still a result of emotional intelligence, to manage, understand, select and work on their emotions in order to generate positive results.

Reactivity also occurs around stress, it is a topic that is in vogue by psychologists and psychiatrists who help humans to combat this disease, since the reactivity index varies in each person due to cognitive and emotional responses, vegetative and behavioral situations in situations that can be potentially harmful, dangerous or unpleasant that condition their way of reacting to internal or external stress factors.

Reactivity in people are affected by circumstances and focus all their efforts in circles of concern over which they have no control and are pessimistic and fatalistic without assuming responsibilities or risks. But reactivity is not only present in the emotional part, but is also seen in the branch of chemistry, where it refers to the ability of an element to combine with others causing a reaction, an example of this happens with the metals as they easily lose their valence electrons and their low ionization energy causing greater reactivity.