Definition of half life

The amount of time it takes for half an initial amount to disintegrate.

The time required for half of a reactant to be converted into product(s). The time required for half of a given sample to undergo radioactive decay. Definition for  Half-Life :The time it takes for one-half of the atoms of an unstable element or nuclide to decay radioactively into another element or nuclide

For a given reaction the half life t1/2 of a reactant is the time required for its concentration to reach a value that is the arithmetic mean of its initial and final (equilibrium) value. For a reactant that is entirely consumed it is the time taken for the reactant concentration to fall to one half of its initial value. For a first-order reaction, the half life of the reactant may be called the half life of the reaction. In nuclear chemistry, (radioactive) half life is defined, for a simple radioactive decay process, as the time required for the activity to decrease to half its value by that process. See also biological half life.

Search the Dictionary for More Terms