Why are some isotopes radioactive and others not? Can you predict which ones will be radioactive?

Answer 1

There are four fundamental forces in nature. They are the strong nuclear and weak nuclear, electro-magnetic, and gravity forces. These all work with and against each other as the universe tries to gain a stable, low ordered state (lowest energy-most random). Also looking at this question, we need to realize that matter is another form of energy, and that energy is the ability to do work. The center of an atom, the nucleus, is held together (work) by converting a little of the mass of the particles of the nucleus into a binding energy. This is needed to keep all those positively charged protons so close to each other. For light elements, if the number of protons and the number of neutrons are the same, all the forces acting in the nucleus are well matched and the nucleus is stable. But if there are too many neutrons or protons, then the nucleus has too much energy and will normally transfer energy around until the 1:1 neutron to proton ratio is achieved. This frequently is seen as the emission of the energy, or what is called radiation. At higher atomic numbers, there are so many protons, that you need more than 1 neutron per proton to hold the nucleus together. However, there still may be stable configurations for the atoms, and the atoms may try to reach those states by emitting the larger alpha particle. Sometimes, following the initial release of energy, there still may be extra energy in the nucleus, and this can be emitted as a photon, or by transferring the energy to the orbital electrons.

Answer 2

Most elements do have a radioactive isotope. In general there is a similar number of neutrons and protons in the lighter elements.. the radioactive isotopes have a larger number of neutrons than the nonradioactive ones. In the larger elements you will notice that the total number of neutrons is increaseing. There is a theory that neutrons try to keep the protons apart. Being positive and likes repelling, more neutrons between the protons makes them more stable. In these the ones with smaller number of neutrons are the radioactive ones. This is an observation, not a rule.Radioactive elements are trying to become more stable by getting rid of some of the nuclear particles..

Answer 3

There is a competition in a nucleus between the repulsive forces of the positive charges, and the attractive forces between nucleons described as the "strong" force. If the repulsive force is bigger, the nucleus will eventually decay, otherwise it will remain stable. We don't have models to make really accurate predictions, but there seems to be a shell structure, similar to the electron shell structure, in which there are preferred numbers of protons and neutrons. An interesting example is the isotope Kr-85, which is one neutron short of filling a shell. This isotope, which is created in a fission reactor (and is radioactive), has an astonishing large appetite for neutrons to fill the last shell spot, and the isotope's presence has major implications when attempting to re-start a reactor that has been shut down.

Answer 4

The stable, non-radioactive isotopes have about the same numbers of protons and neutrons in their nuclei. Get out a periodic table. When you start at hydrogen and go to helium, stability increases; helium is more stable than hydrogen. Then, as you increase the atomic number, elements become less stable. Element 42, technetium, is radioactive, with no stable isotopes. From there they become more stable until you get to element 56, iron, the most stable of all elements. From then on, they steadily become less stable. By the time you get to radium, thorium, polonium and uranium, no elements have any stable isotopes. Why? You need a course in nuclear physics to understand. I understood it in 1973 when I'd just completed such a course, but I've forgotten most of it. Google Weiszäcker's semi-empirical equation to see what I was studying.

Answer 5

theres a chart of radioactivity, and it usually has to do with the ratio of protons to neutrons in a nucleus. the more massive the nucleus, the more it shifts to the neutron heavy isotopes to be stable. It starts out at about 1neutron:1proton and eventually progresses to about 1.5:1 for the more massive nucleii

Answer 6

the ones tht are in a more excited state are and yes you can