Radioactive isotope dating is fallible

02-Jan-2020 10:26 by 10 Comments

Radioactive isotope dating is fallible - best black and white dating sites

A particular isotope of a particular element is called a nuclide. That is, at some point in time, an atom of such a nuclide will undergo radioactive decay and spontaneously transform into a different nuclide.

While the moment in time at which a particular nucleus decays is unpredictable, a collection of atoms of a radioactive nuclide decays exponentially at a rate described by a parameter known as the half-life, usually given in units of years when discussing dating techniques.

In these cases, usually the half-life of interest in radiometric dating is the longest one in the chain, which is the rate-limiting factor in the ultimate transformation of the radioactive nuclide into its stable daughter.

Isotopic systems that have been exploited for radiometric dating have half-lives ranging from only about 10 years (e.g., tritium) to over 100 billion years (e.g., samarium-147).

The rate at which the regeneration takes place has gone virtually unchanged for centuries; a feature which depends on the flux of particles bombarding the earth, and the strength of the magnetic field capable of diverting them.

This magnetic shield, and consequently the particle flux, has slowly changed over time, and the quantity of carbon 14 formed on Earth changes with it.

Stages of Carbon-14 Formation Carbon-14 is continuously generated in the atmosphere by cosmic radiation.

Neutrons are ejected from nuclei of the upper atmosphere in collisions with cosmic rays (A).

The nucleus of carbon 14 contains 6 protons and 8 neutrons, as opposed to the 6 and 6 found in ordinary carbon 12.

The imbalance makes carbon 14 a radioisotope with a half-life of 5,700 years, and an emitter of beta particles.

The radioactive atom is absorbed by plants and living matter in the same way as its non-radioactive isotope ; in every thousand billion (ten to the power of twelve) atoms of carbon 12, there will be on average one atom of carbon 14.

This tiny ratio exists in all molecules involving carbon atms, including all living matter.

Captured by nitrogen nuclei (N-14), neutrons transform these nuclei into carbon-14 (B).