the least amount of energy required to activate atoms or molecules to a state in which they can undergo a chemical reaction.
The least amount of energy needed for a chemical reaction to take place. Some elements and compounds react together naturally just by being close to each other, and their activation energy is zero. Others will react together only after a certain amount of energy is added to them. Striking a match on the side of a matchbox, for example, provides the activation energy (in the form of heat produced by friction) necessary for the chemicals in the match to ignite. Activation energy is usually expressed in terms of joules per mole of reactants.
- Activation record
activation record compiler (Or “data frame”, “stack frame”) A data structure containing the variables belonging to one particular scope (e.g. a procedure body), as well as links to other activation records. Activation records are usually created (on the stack) on entry to a block and destroyed on exit. If a procedure or function may be […]
a person or thing that . Chemistry, Biochemistry. a catalyst. any impurity in a mineral that causes luminescence. Compare (def 3). Orthodontics. a removable appliance, usually of hard plastic, that is worn in the mouth instead of a fixed appliance to help align the teeth and improve the relationship of the lower jaw to the […]
engaged in ; characterized by energetic work, participation, etc.; busy: an active life. being in a state of existence, progress, or motion: active hostilities. involving physical effort and : active sports. having the power of quick motion; nimble: active as a gazelle. characterized by , motion, volume, use, participation, etc.: an active market in wheat; […]
- Active anaphylaxis
active anaphylaxis active anaphylaxis ac·tive anaphylaxis (āk’tĭv) n. The anaphylactic response produced in an individual following inoculation with an antigen to which the person is sensitized.