How do scientists use carbon 14 for radioactive dating
Half the original quantity of carbon-14 will decay back to the stable element nitrogen-14 after only 5,730 years.(This 5,730-year period is called the half-life of radiocarbon, Figure 1).1 2 At this decay rate, hardly any carbon-14 atoms will remain after only 57,300 years (or ten half-lives).These isotopes break down at a constant rate over time through radioactive decay.By measuring the ratio of the amount of the original (parent) isotope to the amount of the (daughter) isotopes that it breaks down into an age can be determined.So, often layers of volcanic rocks above and below the layers containing fossils can be dated to provide a date range for the fossil containing rocks.The atoms in some chemical elements have different forms, called isotopes.Potassium-40 on the other hand has a half like of 1.25 billion years and is common in rocks and minerals.
While people are most familiar with carbon dating, carbon dating is rarely applicable to fossils.
So if fossils are really millions of years old, as evolutionary scientists claim, no carbon-14 atoms would be left in them.
Indeed, if all the atoms making up the entire earth were radiocarbon, then after only 1 million years absolutely no carbon-14 atoms should be left!
Typically commonly occurring fossils that had a widespread geographic distribution such as brachiopods, trilobites, and ammonites work best as index fossils.
If the fossil you are trying to date occurs alongside one of these index fossils, then the fossil you are dating must fall into the age range of the index fossil. In a hypothetical example, a rock formation contains fossils of a type of brachiopod known to occur between 410 and 420 million years.