Scientists now know that most elements come in more than one version. When the dry periods ended and the water level rose, the trees drowned, marking the end of the droughts.
Since then, the remains of those trees have been well preserved by the arid climate. To determine how long ago these droughts occurred, Scott is using carbon-14 to date the trees.
Meet paleoclimatologist Scott Stine, who uses radiocarbon dating to study changes in climate. What we think of as normal carbon is called carbon-12: six protons plus six neutrons. Several times a year, scientist Scott Stine travels to the shores of Mono Lake, near Yosemite National Park. He's studying the long history of droughts in California, trying to determine how frequently they occur and how long they last.Find out what it means for an isotope to be radioactive and how the half-life of carbon-14 allows scientists to date organic materials. But about one percent of carbon atoms have an extra neutron, giving them seven. Over the millennia, the water level has risen and fallen, as the area has cycled between wet periods and dry times. During times when the climate was dry, Mono Lake dropped down, exposed the shore lands, and allowed trees and shrubs to grow. So what we do is we come up with terms that help us get our head around this. So I wrote a decay reaction right here, where you have carbon-14. So now you have, after one half-life-- So let's ignore this. I don't know which half, but half of them will turn into it. And then let's say we go into a time machine and we look back at our sample, and let's say we only have 10 grams of our sample left. Now you could say, OK, what's the probability of any given molecule reacting in one second? But we're used to dealing with things on the macro level, on dealing with, you know, huge amounts of atoms. So I have a description, and we're going to hopefully get an intuition of what half-life means. And how does this half know that it must stay as carbon? So if you go back after a half-life, half of the atoms will now be nitrogen. Then all of a sudden you can use the law of large numbers and say, OK, on average, if each of those atoms must have had a 50% chance, and if I have gazillions of them, half of them will have turned into nitrogen. How much time, you know, x is decaying the whole time, how much time has passed? technology columnist David Pogue explores how isotopes of carbon can be used to determine the age of once-living matter. The difference between them is the number of neutrons in the nucleus.
Learn how variations in atomic structure form isotopes of an element and how the three natural isotopes of carbon differ from each other. Neutrons are electrically neutral particles that act as glue to hold atoms together. And that rare version of carbon has proven to be a crucial tool for unlocking the past.
Radioactive tracers are substances that contain a radioactive atom to allow easier detection and measurement.
(Radioactivity is the property possessed by some elements of spontaneously emitting energy in the form of particles or waves by disintegration of their atomic nuclei.) For example, it is possible to make a molecule of water in which one of the two hydrogen atoms is a radioactive tritium (hydrogen-3) atom.
This molecule behaves in almost the same way as a normal molecule of water.
The main difference between the tracer molecule containing tritium and the normal molecule is that the tracer molecule continually gives off radiation that can be detected with a Geiger counter or some other type of radiation detection instrument.
Nuclear materials (that is, substances that emit nuclear radiation) are fairly common and have found their way into our normal vocabularies in many different ways. In this article, we will look at nuclear radiation so that you can understand exactly what it is and how it affects your life on a daily basis.