Question

放射性元素每次只会有一粒原子进行衰变

Answer 1

更新1:

我的意思 不是切割元素
而是把样本分成两等份 即如果样本中有2mol的粒子 我分2份 都 1mol的粒子

放射性元素每次只会有一粒原子进行放射性衰变 I think you have misunderstood what your physics teacher has said. He/she may mean each radionuclide can only decay once. Because after the decay
the radionuclide will have been changed to nuclide of another element
which may not be radioactive. A sample of radioactive substance contains many many number of radioanuclides. In fact
you cannot tell exactly how many number of these radionuclide would decay in the next second
because radioactive decay is a random process. However
you can tell statistically the expected number of radionuclide which is going to decay in one second. Take
cobalt-60
for example. The decay constant of cobalt-60 is 4.1x10^-9 s^-1. If you have
say
a sample containing 1000 million cobalt-60 radionuclides
there will be statisitcally about 4 cobalt-60 atoms decaying in 1 second. That is to say
a single radionuclide can only decay once. But a radioactive *** aple contains a large number of radionuclides
it can have several radionuclides decaying at the same time. 即每次只会发射出一粒放射物
不会同一时间射出两粒放射物 Depending on the element
a single radionuclide of that element can only emit either an alpha or a beta particles
but not both. In some radionuclides
if the decayed nuclide is in an excited state
gamma rays will be emitted. 为什么不能同一时间放出两粒放射物?? A single radionuclide cannot emit alpha and beta are the same time because "alpha decay" and "beta decay" are in fact o "contradicting processes". Alpha decay occurs in heavy elements (i.e. elements with high atomic number) because of excess number of nuetrons present in the nucleus. Beta decay mostly occurs in light elements in which a neutron changes into a proton and a beta electron (plus a neutrino). 2009-07-12 14:11:20 补充： 那如果我把该样本切开分成 2 块
又会不会同时射出两粒放射物? Sure. Normally
in a sample of radioactive substance
there are many many particles emitting from it in every second.......(cont'd) 2009-07-12 14:12:18 补充： ... (cont'd) When you placed a radiation detector (e.g. a Geiger counter) near a radioactive sample
you could observe the count-rate recorded by the Geiger counter. ......(cont'd) 2009-07-12 14:12:49 补充： ....(cont'd) The number of counts in 1 second
in fact
indicates the the number of particles emitting from the sample and entering into the Geiger tube. Count-rates of several hundreds to several thousands counts in 1 second are not unon.
当你把该元素切成2块，它就已经不是放射性元素了。(请给我分 please)
参考: 个人经验