How are isotopes used to analyze things?
In: Chemistry
Since isotopes mostly work the same as the common version of the element, you can use them like tiny “tags” to see how much or how fast a process proceeds. If you use heavy water to feed a plant, you can see where the most recently absorbed water went inside the plant
So, due to a whole confluence of natural processes, different isotopes of each element tend to be more or less common. In radioactive dating, we can take advantage of this. For example, Carbon 14 is formed in the upper atmosphere. Any cell that’s exchanging oxygen and CO2 will end up with a pretty similar proportion of C-12 to C-14 in its body. However, since C-14 is way less stable, once the animal dies, the proportion of C-14 will go down. Since radioactive decay happens at a predictable rate, we can reliably time when a fossil stopped breathing.
The simple idea that isotopes are unstable can be helpful, too. If you inject someone with an isotope that gives off low levels of a safer type of radiation, you can use imaging devices that detect that radiation to visualize a person’s interior. This is how lots of medical imaging works.
These are just a couple of broad examples.
Some isotopes are radioactive, but they behave like the regular elements, this is helpful to tell where a particular substance goes
For example you can give radioactive nutrients to a bacteria and then separate all the different things the bacteria makes and see which ones are the most radioactive
Iron has for stable isotopes:
* Fe-54 – 6%
* Fe-56 – 92%
* Fe-57 – 2%
* Fe-58 – trace
Iron in the earth mostly occurs in those same proportions, but not exactly. Iron from a meteorite is likely to have a different composition of isotopes than one from a mine, so be measuring these values we can tell the difference.
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