Radiocarbon dating for idiots
So you might get a question like, I start with, oh I don't know, let's say I start with 80 grams of something with, let's just call it x, and it has a half-life of two years. 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. In recognition of his work, he was awarded the Nobel Prize in chemistry in 1960.SAL: In the last video we saw all sorts of different types of isotopes of atoms experiencing radioactive decay and turning into other atoms or releasing different types of particles. This is also actually kind of trivial and easily determined in the lab. Let’s see what the Missing Universe Museum thinks are the assumptions of radioactive dating methods. I guess we have to start at the top and work our way down… During an organisms life, it takes in CO have the common 6 protons and 6 neutrons. However, due to some interesting nuclear chemistry (which I’ll go into if requested), there’s another version of carbon (called an isotope) that has 6 protons and 8 neutrons. Note that if the number of protons change, then the atom is no longer carbon. Amazingly (and unlike what is claimed by the creationists), scientists have known about a variety of methods that create carbon-14 and how those methods have varied over time. Well, we take a carbon sample from a material of a known age and date that. Basically, the calibration curves are off by no more than 16 years over the historical range (6,000 years or so) and no more than 163 years over the last 20,000 years.Indeed, by doing almost 20 seconds of research on google (type in “variations in C14”, click on Google Scholar) the second link is this article from 1954: Carbon 13 in plants and the relationships between carbon 13 and carbon 14 variations in nature So, this issue has been known about for a long time. Then we compare the two and adjust the radiocarbon date to the known date. That’s less than 1% if you’re interested in that sort of thing. But this is already almost a thousand words and I’ve only done ONE! Long story short, scientists have always known that variations in C-14 concentration happen.
Let's say I have a bunch of, let's say these are all atoms. And let's say we're talking about the type of decay where an atom turns into another atom. Or maybe positron emission turning protons into neutrons. And we've talked about moles and, you know, one gram of carbon-12-- I'm sorry, 12 grams-- 12 grams of carbon-12 has one mole of carbon-12 in it.
Discovered by Willard Frank Libby and his colleagues in 1949, during his tenure as a professor at the University of Chicago, Libby invented what would eventually change the face of archaeology by giving a time frame to fossilized specimens.
Libby estimated that the steady state radioactivity concentration of exchangeable carbon-14 would be about 14 disintegrations per minute (dpm) per gram.
Scientists look at half-life decay rates of radioactive isotopes to estimate when a particular atom might decay.
A useful application of half-lives is radioactive dating.