lnm Posted May 12, 2010 Share Posted May 12, 2010 I know that half life is the time period for half the radioactive nuclei to decay. That if the half life of carbon 13 is 1000years... in a thousand years you'll have half the amount of carbon 13 as you did when you started. These are the sorts of explanations I can find but I would like to know what is actually happening. If I have one carbon 13 atom, do I end up with half the atom? Does it eventually disappear? What exactly is "radioactive decay"? Link to comment Share on other sites More sharing options...
Double K Posted May 12, 2010 Share Posted May 12, 2010 What exactly is "radioactive decay"? The measure of energy dissipation? You don't end up with half an atom, but it now carries half of its energy and transforms the element eg carbon14 becomes nitrogen14 Link to comment Share on other sites More sharing options...
Mr Skeptic Posted May 12, 2010 Share Posted May 12, 2010 Each atom decays completely or not at all. For carbon 14, there's about 4 = 4.3 × 10^22 atoms in a gram. Or if you prefer, 43,000,000,000,000,000,000,000 atoms in a gram. Half of them will decay, half will not. Eventually, you will end up with no atoms at all, or perhaps there might still be an atom when you'd "expect" to find half an atom. Link to comment Share on other sites More sharing options...
ewmon Posted May 12, 2010 Share Posted May 12, 2010 We can look at radioactive decay in more than one way. We can look at numbers of isotopes that decay over a certain amount of time, or we can look at the probability of a single isotope decaying. It's like flipping 10,000 coins, and realizing that you'll end up with about 5,000 heads and 5,000 tails. Or, you can look at only one coin and realize that, when you flip the coin, there''s a 50% probability it'll be heads and a 50% probability it'll be tails. Same thing for isotopes. Over the course of 5,730±40 years, there's a 50% probability that a Carbon-14 isotope will decay to Nitrogen-14, and a 50% probability that it won't. When you look at large populations over this time span, half of them will decay and half of them won't. This decay has a non-linear relationship with time, which is called an "exponential decay". Personally, I'm disappointed with this question, as I assumed from the title that it was about the Half-Life computer game. Link to comment Share on other sites More sharing options...
vordhosbn Posted May 12, 2010 Share Posted May 12, 2010 Personally, I'm disappointed with this question, as I assumed from the title that it was about the Half-Life computer game. +1 I also thought that this thread will be concerned with inter-dimensional scientists. Link to comment Share on other sites More sharing options...
the tree Posted May 12, 2010 Share Posted May 12, 2010 Each atom decays completely or not at all. For carbon 14, there's about 4 = 4.3 × 10^22 atoms in a gram. Or if you prefer, 43,000,000,000,000,000,000,000 atoms in a gram. Half of them will decay, half will not. Eventually, you will end up with no atoms at all, or perhaps there might still be an atom when you'd "expect" to find half an atom.This. After one half-life, the probability of any individual isotope having decayed is 0.5. Strictly speaking it's only really called an atom when it has the right number of electrons to neutrons. A carbon-13 isotope has one too many neutrons which makes it unstable so it breaks apart. Exactly when this will happen is impossible to predict (like, literally impossible - quantum indeterminacy kicks in on this scale) which is why half-lives which are really just a statistical average are used to predict how many out of a large number isotopes will have decayed after a given amount of time. Link to comment Share on other sites More sharing options...
ewmon Posted May 12, 2010 Share Posted May 12, 2010 Exactly when this will happen is impossible to predict Oh ... I thought we could just take the derivative of the exponential decay ... So, if a Carbon-14 isotope has a 50% probability of decaying every 5,730 years, then it has about a 1.2% chance of decaying every 100 years. Link to comment Share on other sites More sharing options...
Mr Skeptic Posted May 12, 2010 Share Posted May 12, 2010 Right, the chance of decay is constant at all times. However, that does not tell you when it will decay. You can't say, 100 years from now, these 6 atoms will decay and these 500 other atoms will not. Link to comment Share on other sites More sharing options...
swansont Posted May 12, 2010 Share Posted May 12, 2010 You don't end up with half an atom, but it now carries half of its energy Um, no. Link to comment Share on other sites More sharing options...
lnm Posted May 12, 2010 Author Share Posted May 12, 2010 I am very thankful for every reply but I am still sort of confused. What, exactly, is radioactive decay? What is it that happens to an atom? Does it loose an electron/proton/neutron and is now a different element/isotope? Does the speed of any particle in it slow down and this is what a lose of energy means? Does a particle in it evaporate and ultimately I would end up with no atom at all? I am more interested in what is actually happening than in when it will happen or what the probability of it occurring is. Link to comment Share on other sites More sharing options...
Moontanman Posted May 12, 2010 Share Posted May 12, 2010 I am very thankful for every reply but I am still sort of confused. What, exactly, is radioactive decay? http://en.wikipedia.org/wiki/Radioactive_decay What is it that happens to an atom? Does it loose an electron/proton/neutron and is now a different element/isotope? Does the speed of any particle in it slow down and this is what a lose of energy means? Does a particle in it evaporate and ultimately I would end up with no atom at all? An atom emits one or more of several particles, resulting in a new atom of either lower energy or a different element and lower energy. In some atoms they do indeed split into two smaller atoms but more often a particle of some sort is emitted. if the process continued on down to it's lowest possible denominator you would end up with a hydrogen atom, protons are believed to be ultimately stable. Link to comment Share on other sites More sharing options...
Sisyphus Posted May 12, 2010 Share Posted May 12, 2010 Does it loose an electron/proton/neutron and is now a different element/isotope? This one. And by "lose" it should be noted that whatever is lost doesn't just disappear - it is ejected. So for example, the nucleus of carbon-14 has 6 protons and 8 neutrons. One of the neutrons breaks apart into a proton and an electron, and the electron is emitted, leaving behind 7 protons and 7 neutrons: nitrogen-14. Link to comment Share on other sites More sharing options...
TheLivingMartyr Posted May 19, 2010 Share Posted May 19, 2010 I am very thankful for every reply but I am still sort of confused. What, exactly, is radioactive decay? What happens to the atom of a radioisotope (an element with a different number of neutrons, making it unstable) is that it emits radiation. the types of radiation are: Alpha: the nucleus emits a helium nucleus (2 protons, 2 neutrons, with no electrons) this obviously means that the atomic mass of the element decreases by 4 Beta: the atom emits an e- particle (an electron) Gamma: the atom emits gamma rays (photons, and this form of radiation occurs along side alpha radiation) if you would like me to explain what these certain types of radiation can do, then i will be happy to:-) Link to comment Share on other sites More sharing options...
swansont Posted May 19, 2010 Share Posted May 19, 2010 What happens to the atom of a radioisotope (an element with a different number of neutrons, making it unstable) is that it emits radiation. the types of radiation are: Alpha: the nucleus emits a helium nucleus (2 protons, 2 neutrons, with no electrons) this obviously means that the atomic mass of the element decreases by 4 Beta: the atom emits an e- particle (an electron) Gamma: the atom emits gamma rays (photons, and this form of radiation occurs along side alpha radiation) if you would like me to explain what these certain types of radiation can do, then i will be happy to:-) Beta decay also emits a neutrino or antineutrino. Gamma radiation is emitted with beta decays as well; alpha decays often leave the system in the ground state with no gamma emission. Link to comment Share on other sites More sharing options...
TheLivingMartyr Posted May 20, 2010 Share Posted May 20, 2010 doesn't it emit a neutrino by converting one of it's neutrons into a proton by emitting an electron and a neutrino? Link to comment Share on other sites More sharing options...
swansont Posted May 20, 2010 Share Posted May 20, 2010 doesn't it emit a neutrino by converting one of it's neutrons into a proton by emitting an electron and a neutrino? electron and antineutrino for beta -, positron and neutrino for beta + Link to comment Share on other sites More sharing options...
TheLivingMartyr Posted May 20, 2010 Share Posted May 20, 2010 (edited) okay thanx Merged post follows: Consecutive posts mergedi'm assuming that it's an electron neutrino? not for some random reason a muon or tauon neutrino Merged post follows: Consecutive posts mergedoooo, i found a good feynmann diagram that explains Beta- decay http://upload.wikimedia.org/wikipedia/commons/8/89/Beta_Negative_Decay.svg the down quark of the neutrons decays into an up quark, by emitting a W- boson, which then decays into an electron and an electron neutrino Edited May 20, 2010 by TheLivingMartyr Consecutive posts merged. Link to comment Share on other sites More sharing options...
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