From Wikipedia (see the Related Link below):
By emitting an electron and an anti-neutrino, carbon-14 is changed into stable (non-radioactive) nitrogen-14. This decay can be used to get a measure of how long ago a piece of once-living material died. However, aquatic plants obtain some of their carbon from dissolved carbonates which are likely to be very old, and thus deficient in the carbon-14 isotope, so the method is less reliable for such materials as well as for samples derived from animals with such plants in their food chain.
The reaction is:
146C ---> 147N + e- + antineutrino
Three isotopes of carbon are carbon-12, carbon-13, and carbon-14. Isobars of carbon are elements with the same mass number, such as nitrogen-14 and oxygen-14.
No, carbon-12 and carbon-14 are both forms of carbon with the same chemical properties. Carbon-12 has 6 neutrons, while carbon-14 has 8 neutrons, which makes it radioactive but doesn't affect its reactivity.
Isotopes.
Carbon-12 has 6 protons and 6 neutrons, whereas carbon-14 has 6 protons and 8 neutrons. Carbon-12 is stable and makes up the majority of carbon found on Earth, while carbon-14 is radioactive and is used in radiocarbon dating to determine the age of organic materials.
The atomic number of carbon is 6. Carbon-14 is an isotope of carbon with 6 protons and 8 neutrons.