# Potassium 40 dating

The decrease in the amount of potassium required to form the original mineral has consistently confirmed the age as determined by the amount of argon formed.

Carbon-14 dating: See Carbon 14 Dating in this web site.

If we knew the fraction of a radioactive element still remaining in a mineral, it would be a simple matter to calculate its age by the formula To determine the fraction still remaining, we must know both the amount now present and also the amount present when the mineral was formed.

Contrary to creationist claims, it is possible to make that determination, as the following will explain: By way of background, all atoms of a given element have the same number of protons in the nucleus; however, the number of neutrons in the nucleus can vary.

The two curves cross each other at half life = 1.00.

At this point the fraction of Rb87 = Sr87 = 0.500; at half life = 2.00, Rb87 = 25% and Sr87 = 75%, and so on. 131, Strahler, Science and Earth History: Points are taken from these curves and a plot of fraction Sr-87/Sr-86 (as ordinate) vs. It turns out to be a straight line with a slope of -1.00.

The creationist "argon escape" theory does not support their young earth model.) The argon age determination of the mineral can be confirmed by measuring the loss of potassium.

In old rocks, there will be less potassium present than was required to form the mineral, because some of it has been transmuted to argon.

We designate a specific group of atoms by using the term "nuclide." A nuclide refers to a group of atoms with specified atomic number and mass number.Strontium-86 is a stable element that does not undergo radioactive change.In addition, it is not formed as the result of a radioactive decay process.Potassium-Argon dating: The element potassium (symbol K) has three nuclides, K39, K40, and K41. K40 can decay in two different ways: it can break down into either calcium or argon.The ratio of calcium formed to argon formed is fixed and known.