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Radioactive Decay
Also known as nuclear decay, radioactive decay is the decrease of radiation through time.
540 Questions
That depends on the energy of the beta particles and the medium they are passing through.
In air beta can travel several inches to several feet.
Beta cannot pass through a single layer of aluminum foil.
How do scientist predict when an atom will undergo radioactive decay?
Scientists predict when an atom will undergo radioactive decay using the concept of half-life, which is the time required for half of a sample of a radioactive isotope to decay. Each isotope has a characteristic half-life that is statistically determined based on its decay rate. While the exact moment of decay for an individual atom cannot be predicted, the decay of a large number of atoms can be modeled accurately over time. Additionally, quantum mechanics plays a role in understanding the probabilistic nature of radioactive decay.
What happens to radioactive materials if you do not use them?
That depends on the radioactive material. But whether you use it or not, the radioactive material will decay into other elements over the course of time. The time it takes for half of the material to decay into something else is called the "half-life". The more radioactive the substance is, the faster it decays. The half-life of a radioactive element can be measured from fractions of a second to billions of years.
How can radioactive decay be used?
Radioactive decay can be used in quite a few ways including:
- Heat source - some space probes use this feature to poweron-boardinstruments by using the heat of the decay to power thermocouples.
- Sample dating - the decay of radioisotopes can be measured to indicate that total amount of residual radioisotope. If the original content of a sample is known, the residual amount can be used to date the sample. This is the principle of "carbon-dating" where the original concentration is assumed to be the same as current steady-state concentrations of 14C.
- Cancer treatment - decay of radioisotopes can produce radiation that damages faster growing cells more than slow growing ones. Since cancer is faster growing, it affects cancer cells more than normal ones. Unfortunately hair cells and the lining of the intestine are also rather fast growing, thus causing the characteristic loss of hair and intestinal problems often associated with cancer treatments
- Jump starting nuclear reactions - the decay of existing radioisotopes produces the particles that can start chain reactions and get fission reactions going. Typically you have to confine the reaction and slow down the decay particles enough to sustain the reaction.
What kinds of changes to a nucleus occur for each kind of nuclear decay?
In alpha decay, the nucleus loses 2 protons and 2 neutrons. This causes the atomic number to decrease by 2, thus a new element is formed. The mass also changes by 4. Extra energy is also released as gamma radiation.
In beta decay, one neutron in the nucleus changes into a proton and the nucleus emits a beta particle (the electron). Also gamma rays may be released calling away extra energy. The nucleus now has 2 more proton so the atomic number increases by 1 and again a new different element has been formed. The mass number of the isotope is still the same.
What would Americium transmute into if it expelled an alpha particle?
For example americium-241 decay to neptunium-237 and americium-243 decay to neptunium-239.
Why is now mass spectroscopy used instead of radiocarbon dating?
Mass spectrometry has not replaced radiocarbon dating, it is used as a better way to measure the amount of carbon-14 in the sample that permits smaller sample sizes and improved accuracy.
How many days until one-sixteenth of a 54.2 g sample of thorium-234 remains?
The half-life of thorium-234 is about 24 days. Therefore, it would take approximately 96 days for one-sixteenth of the original 54.2 g sample of thorium-234 to remain.
What is the nuclear decay equation for zirconium-97?
The equation for the beta decay of 97Zr is:
4097Zr --> 4197Nb + -10e
representing the beta particle as -10e.
Does the element aluminum undergo radioactive decay?
All elements have some isotopes that undergo radioactive decay, the question is how fast.
Aluminum comes in three major isotopes, each with their own half-life:
- Al-26: 730000 years - 0% in natural aluminum
- Al-27: Stable - 100% in natural aluminum
- Al-28: 2.3 minutes - 0% in natural aluminum
So as natural aluminum is 100% Al-27 it does not undergo radioactive decay
What are examples of nuclear changes in mass?
Changes in nuclear mass can happen when, say, radioactive decay occurs and a nucleus loses mass. When an unstable atomic nucleus "adjusts" to a new state, it dumps a particle or particles, and energy, and its mass decreases. Certainly nuclear fission will cause a dramatic reduction in nuclear mass, but this is the actual "breaking up" of a nucleus into smaller nuclei called fission fragments. Perhaps an example will help. The element radon is an inert gas, but it has no stable isotopes. It's most stable isotope, 222Rn, appears as a decay product of radium; it's a radioactive daughter. It turns out that 222Rn decays by alpha emission, and that means that two neutrons and two protons are kicked out of the nucleus. This will produce the radioactive daughter product polonium-218. It is possible for a nucleus to absorb a particle and gain mass. Frequently this will cause nuclear instability (if it doesn't actually initiate fission) and create a radionuclide, which is unstable and will eventually decay. But something like, say, neutron absorption (neutron capture) will result in an atomic nuclei with a greater mass than the original atomic nucleus that absorbed that neutron. It is of note that fusion knits smaller nuclei or particles together to create a larger nucleus, but this may not necessarily be considered a "simple increase" of mass in a nucleus, though the resultant nucleus will be heavier than any constituent nucuei or particles. You may want an example. If we stick some uranium-238 into an operating nuclear reactor, the 238U will absorb a neutron to become 239U, which is heavier by one neutron that the atomic nucleus that absorbed that neutron. (The 239U is unstable and decays in a couple of steps to make 239Pu, which is used as the fissile material in most nuclear bombs and as a fuel in some nuclear reactors.) Use the links below to related articles posted by our friends at Wikipedia, where knowledge is free.
When a radioactive isotope decays, it may convert to another isotope which is, again, unstable. The "decay chain" refers to the complete list of all the intermediate products, until a stable isotope is reached.
