Carbon-14
Definition and meaning of Carbon-14 in chemistry.
Carbon-14 is a special radioactive version of the normal carbon atom. The nucleus of this atom contains exactly six protons and eight neutrons. It is famous for helping scientists figure out the age of ancient objects.
In more detail
Carbon-14 is constantly formed high up in the Earth's atmosphere. Cosmic rays from space crash into nitrogen atoms and change them into carbon-14. This radioactive carbon mixes with oxygen to form carbon dioxide gas.
Plants breathe in this radioactive gas during a process called photosynthesis. Animals then eat the plants, moving the carbon-14 up the food chain. While a plant or animal is alive, its carbon-14 level stays perfectly constant.
It replaces any lost carbon-14 by eating more food or breathing. But when the living organism dies, it stops taking in new carbon. The trapped carbon-14 atoms slowly begin to break down into nitrogen-14.
This radioactive breakdown happens at a very steady rate called a half-life. The officially measured half-life of carbon-14 is approximately 5,730 years. This means half of the carbon-14 will disappear every 5,730 years.
Scientists can measure how much carbon-14 is left in an old bone. They compare it to a living bone to see how much has vanished. This math lets them calculate exactly how long the animal has been dead. This technique is known around the world as radiocarbon dating.
Key facts
| Field | Analytical Chemistry |
|---|---|
| Symbol | ¹⁴C (or C-14) |
| Protons | 6 |
| Neutrons | 8 |
| Decay mode | Beta-minus decay to nitrogen-14 |
| Half-life | 5,730 ± 40 years |
Imagine a wooden artifact is found at an ancient campsite. Scientists measure its carbon-14 level and compare it to fresh wood. They find the old wood only has 25 percent of its original carbon-14. This means the carbon has gone through two complete half-lives. It dropped from 100 percent to 50 percent, and then to 25 percent. We simply multiply the half-life of 5,730 years by two. This tells us the wooden artifact is roughly 11,460 years old.
Frequently asked questions
Why is carbon-14 radioactive while carbon-12 is stable?
Carbon-14 has two extra neutrons compared to normal carbon-12. This makes the nucleus unstable, so it shoots out particles to reach a stable state.
Can carbon-14 date dinosaur bones?
No, carbon-14 decays way too quickly to measure millions of years. It is only useful for objects that are less than 50,000 years old.
Does carbon-14 harm us?
Carbon-14 does not harm us because the amount in our bodies is incredibly small. The very low level of radiation is just a normal part of our natural environment.