added to [[ classical physics]] (in the 1920s) an understanding how particles behave inside [[atom]] s. Quantum mechanics posits that an [[ electron]] (or any other [[sub- atomic particle]] ) behaves as both a [[ wave]] and a [[ particle]]. Quantum mechanics forms the basis for our understanding of chemical reactions, as well as all computers and electronic devices today.
As a result of the wave nature of the electron, the position of the electron can never be precisely known. Whenever it is attempted to be measured, knowledge of the electron's [[velocity]] is lost. Hence, there is an inherent uncertainty that prevents precisely measuring both the position and the momentum simultaneously. This is known as the [[Heisenberg Uncertainty Principle]].
An important aspect of Quantum Mechanics is the predictions it makes about the [[radioactive decay]] of [[isotopes]]. Radioactive decay processes, controlled by the wave equations, are random events. A radioactive atom has a certain probability of decaying per unit time. As a result, the decay results in an exponential decrease in the amount of isotope remaining in a given sample as a function of time. The characteristic time required for 1/2 of the original amount of isotope to decay is known as the "half-life" and can vary from quadrillionths of a second to quintillions of years.
:* [[Erwin Schrodinger]], [[Schrodinger equation]]
*[[Heisenberg uncertainty principle]]
For an excellent discussion of quantum mechanics, see: