Strontium, for example, has four stable isotopes: Sr, Sr, Sr, and Sr; and one radioactive isotope, Sr Over time, Sr decays to rubidium with a half-life of 25 days, making it suitable for use in generators to provide rubidium, the most convenient positron emission tomography agent for heart imaging. Twenty-six elements only have one stable element, while tin has the most stable isotopes with ten. The approximately ninety naturally occurring elements are estimated to occur as different isotopes, of which roughly are stable and 35 are unstable radioactive with extremely long half-lives of millions of years.
More than 3, additional radioactive isotopes have been artificially created. In nature, most elements are comprised of a mixture of isotopes. Isotopes can either form spontaneously naturally through radioactive decay of a nucleus i. In some cases, a new isotope of the same element is produced. In other cases, an element is converted to another element in a process called "transmutation. As radioisotopes naturally decay, particles deposit i. Alpha particles energy is deposited across the shortest distance and, therefore, is "stopped" the most easily.
Beta particles require slightly more protection, and photons gamma rays and X rays need much greater shielding. Neutron radiation is considered the most severe and dangerous to humans due to its high kinetic energy, so it typically requires the most significant shielding. Materials with low atomic numbers water, carbon, lithium, etc. Isotopes page.
Perhaps you were referring more to isotopes in nature. The difference between these processes is not important; however they both involve the absorption of neutrons by nuclei followed by beta decay the process by which a neutron in the nucleus is converted into a proton or vice verse.
In large stars, there are enough neutrons that a nucleus can absorb many neutrons before it has time to decay. Depending on the number of neutrons absorbed, the isotope of the final product can vary. Unfortunately, if you are looking for a more in depth answer, then we must begin delve into nuclear physics always a fun topic.
The stability of a nucleus is governed largely by the binding energy which incorporates the volume, surface, coulomb, symmetry and pairing energy of the nucleons. Each of these terms is dependent upon the mass and charge of the nucleus. Ergo, Isotopes. Pages: [ 1 ] Go Up. Chemically, all three are indistinguishable, because the number of electrons in each of these three isotopes is the same. So different isotopes of the same element are identical, chemically speaking.
But some isotopes have the ability to circumvent this rule by transforming into another element entirely. This transformative ability some isotopes have has to do with the fact not all isotopes are stable, and is what led Frederick Soddy to his Nobel Prize-winning discovery of isotopes in Some isotopes - such as carbon - will happily continue to exist as carbon unless something extraordinary happens.
Others - carbon, say - will at some point decay into a stable isotope nearby. In this case, one of the neutrons in carbon changes into a proton, forming nitrogen During this process, which is known as beta decay , the nucleus emits radiation in the form of an electron and an antineutrino.
There are many factors that can cause a nucleus to decay. One of the most important is the ratio of protons to neutrons a particular nucleus has. The same is true if a nucleus has too many protons. This is one of the reasons why some isotopes of a given element are radioactive, while others are not.
By now, you may be wondering how all these isotopes were created in the first place. As it turns out, this question is a complex one, but lends some truth to the adage that we are all made of star dust.
Some of the lighter isotopes were formed very early in the history of the universe, during the Big Bang. Others result from processes that happen within stars or as a result of chance collisions between highly energetic nuclei - known as cosmic rays - within our atmosphere.
Most naturally existing isotopes are the final stable or long-lived product resulting from a long series of nuclear reactions and decays.
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