Does radiometric dating always involve carbon

Since the atmosphere is composed of about 78 percent nitrogen,2 a lot of radiocarbon atoms are produced—in total about 16.5 lbs. These rapidly combine with oxygen atoms (the second most abundant element in the atmosphere, at 21 percent) to form carbon dioxide (CO This carbon dioxide, now radioactive with carbon-14, is otherwise chemically indistinguishable from the normal carbon dioxide in the atmosphere, which is slightly lighter because it contains normal carbon-12.

does radiometric dating always involve carbon-9

But there is no way of independently calibrating the radioactive clocks in rocks because no observers were present when the rocks formed and the clocks started. And because the half-life of carbon-14 is just 5,730 years, radiocarbon dating of materials containing carbon yields dates of only thousands of years, not the dates over millions of years that conflict with the framework of earth history provided by the Bible, God’s eyewitness account of history.

So one would think that since the radiocarbon dating method works on organic (once-living) materials, then radiocarbon could be used to date fossils.

If we assume that the mammoth originally had the same number of carbon-14 atoms in its bones as living animals do today (estimated at one carbon-14 atom for every trillion carbon-12 atoms), then, because we also know the radiocarbon decay rate, we can calculate how long ago the mammoth died. This dating method is also similar to the principle behind an hourglass (figure 4).

The sand grains that originally filled the top bowl represent the carbon-14 atoms in the living mammoth just before it died.

Chemists have already determined how many atoms are in a given mass of each element, such as carbon.4 So if we weigh a lump of carbon, we can calculate how many carbon atoms are in it.

If we know what fraction of the carbon atoms are radioactive, we can also calculate how many radiocarbon atoms are in the lump.

After plants and animals perish, however, they no longer replace molecules damaged by radioactive decay.

Instead, the radiocarbon atoms in their bodies slowly decay away, so the ratio of carbon-14 atoms to regular carbon atoms will steadily decrease over time (figure 3).

Knowing the number of atoms that decayed in our sample over a month, we can calculate the radiocarbon decay rate.

The standard way of expressing the decay rate is called the half-life.5 It’s defined as the time it takes half a given quantity of a radioactive element to decay.

Next comes the question of how scientists use this knowledge to date things.

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