Start The kinetics of radioactive decay and radiometric dating

The kinetics of radioactive decay and radiometric dating

Gamma emission (γ emission) is observed when a nuclide is formed in an excited state and then decays to its ground state with the emission of a γ ray, a quantum of high-energy electromagnetic radiation.

Beta (β) decay is the emission of an electron from a nucleus.

Iodine-131 is an example of a nuclide that undergoes β decay: Beta decay, which can be thought of as the conversion of a neutron into a proton and a β particle, is observed in nuclides with a large n:p ratio.

In most cases, the energy emitted will be in the form of an X-ray.

Like positron emission, electron capture occurs for “proton-rich” nuclei that lie below the band of stability.

The radiation produced during radioactive decay is such that the daughter nuclide lies closer to the band of stability than the parent nuclide, so the location of a nuclide relative to the band of stability can serve as a guide to the kind of decay it will undergo ([link]).

Although the radioactive decay of a nucleus is too small to see with the naked eye, we can indirectly view radioactive decay in an environment called a cloud chamber.

By the end of this section, you will be able to: * Recognize common modes of radioactive decay * Identify common particles and energies involved in nuclear decay reactions * Write and balance nuclear decay equations * Calculate kinetic parameters for decay processes, including half-life * Describe common radiometric dating techniques Following the somewhat serendipitous discovery of radioactivity by Becquerel, many prominent scientists began to investigate this new, intriguing phenomenon.

Among them were Marie Curie (the first woman to win a Nobel Prize, and the only person to win two Nobel Prizes in different sciences—chemistry and physics), who was the first to coin the term “radioactivity,” and Ernest Rutherford (of gold foil experiment fame), who investigated and named three of the most common types of radiation.

Alpha (α) decay is the emission of an α particle from the nucleus. Because the loss of an α particle gives a daughter nuclide with a mass number four units smaller and an atomic number two units smaller than those of the parent nuclide, the daughter nuclide has a larger n:p ratio than the parent nuclide.

If the parent nuclide undergoing α decay lies below the band of stability (refer to [link]), the daughter nuclide will lie closer to the band.

We now know that α particles are high-energy helium nuclei, β particles are high-energy electrons, and γ radiation compose high-energy electromagnetic radiation.