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1. Hello,

Carbon-14 decays to Nitrogen and that's it? so the half life is found by a single carbon 14 atom changing to nitrogen only, which takes about 5730 years, after that nitrogen doesnt't decay right? so basically we know the half life of carbon 14 when a carbon 14 atom decays to a nitrogen atom right?

Thanks

From John Wood
2. half life is the average amount of time for half the nuclei in a sample to decay.

radioactive decay is a totally random process, if you had one carbon-14 atom you would have no idea when it would decay. It could be in the next few seconds or it could take a million years.

The half life of carbon-14 will be measured by measuring the activity of many different samples and then calculating an average halflife, which would be in the region of 5700 years. It would be by no means exact.

It would actually be quite impossible to measure the half life of an isotope if you had just one atom.

3. so half life is not the amount of time a single for example carbon 14 atom takes to decay its the time taken for half a bunch of atoms to decay to nitrogen? so say you have 100 atoms decay is how long it takes to decay to 50?
4. You then use this:

N=Noe^[landa]t

and use simple logs to work it out.
5. I dont understand that?
6. A half life is the time taken for a process to occur. In terms of physics... a half-life is the time taken for half the radioactive nuclei to decay.
7. yeah ok so 'the time taken for half the radioactive nuclei to decay' does that mean a bunch of radioactive atoms decaying to half? or the time taken for one single atom decaying to half?

Thanks

From John Wood
8. It's the time taken for "a bunch of radioactive nuclei to decay by half" => you'll be left with half the bunch of radioactive nuclei for this given time [half-life].
9. (Original post by Neo1)
so half life is not the amount of time a single for example carbon 14 atom takes to decay its the time taken for half a bunch of atoms to decay to nitrogen? so say you have 100 atoms decay is how long it takes to decay to 50?
Correct yes. if you start with 100 the half life is the time taken for 50 to decay, after two half lives the number of undecayed nuclei will have decreased to 25 etc...
10. Half life is the amount of time taken for the radioactivity to reduce by half, no matter what radioactivity you begin with. The radioactivity is the number of atoms left undecayed, so it's for the whole radioactive source.

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