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Radioactive Decay
Also known as nuclear decay, radioactive decay is the decrease of radiation through time.
540 Questions
How do radioactive rays behave in an electric and magnetic field?
That will depend on their electric charge: plus and minus charged rays will behave in opposite ways while uncharged rays will not be affected at all by the fields.
Where does radioactive decay take place?
Radioactive decay happens to the unstable atom nuclei in its efforts striving to reach stability. The nucleus of any element atom should have specific neutron/proton ratio to be a stable nucleus. Also, the absolute number of protons should not exceed certain limit.
For a nucleus with neutron/proton is higher than the stability ratio, two types of radioactive decay may occur to decrease the ratio in the nucleus in order to reach stability:
- radioactive beta decay: in which a neutron transforms into proton plus electron where the proton remains in the nucleus and the electron is emitted from the nucleus as beta radiation
- radioactive neutron decay: in which a neutron is emitted from the nucleus as neutron radiation (this transformation is relatively rare. Example of this transformation is the unstable Krypton-87)
For a nucleus with neutron/proton is lower than the stability ratio, two types of radioactive decay may occur to increase the ratio in the nucleus in order to reach stability:
- radioactive proton decay: in which a proton in the nucleus transforms into neutron plus positron where the neutron remains in the nucleus and the positron is emitted from the nucleus as positive beta radiation
- proton attraction of one electron from the nearest orbit to the nucleus to form neutron that remains in the nucleus.
For an unstable nucleus with number of protons exceeding the stability limit, the nucleus may reach stability with one or more of the above four nuclear transformations or by:
- fission of the nucleus into two or more smaller nuclei with emission of one or more neutrons (as the spontaneous fission of one of the plutonium isotopes).
A researcher who uses carbon dating on anciet items?
The half life of C14 is about 5700 years, so items that are a few multiples of this time are suitable for carbon14 dating. Most archaeological items are suitable, and some young fossils.
Where did most of the alpha particles fired at the foil go in the gold foil experiment?
Most of them went right through.
Radiocarbon dating, or Carbon 14 dating, relies on processes of radioactive decay. It can be used on any organic matter.
Every living thing contains carbon. When something dies its body stops taking in carbon. From this point onwards the carbon in the body will begin to decay.
It takes roughly 5568 years for the half the carbon in any sample to decay (this is its half life) Decay is at a relatively constant rate. By looking at how much carbon remains in a sample it is possible to calculate how long ago it stopped taking in new carbon (when it died).
There is always an error range associated with results, which is given with a + and - sign. A result of 550 +-50 BC means that a sample is likely to date from 500-600BC.
Carbon dating is accurate up to roughly 50,000 years ago. After this the rate of decay is too small to get accurate dates from a sample, and other dating methods (such as Thermoluminescence and Potassium-Argon) have to be used.
Can all radioactive isotopes be used in radiometric dating?
No, not all radioactive isotopes be used in radiometric dating. Some have very very short half lives and would entirely disappear before any useful period of time passed.
Technetium is an artificial element with applications as:
Technetium-99m is largely used as tracer in radiodiagnostic.
Technetium-99 is used as standard source for beta radiation.
Technetium-95m is used as tracer in environmental studies.
Carbon dating can be used to measure the age of each the following except?
Carbon dating can be used to measure the age of organic materials.
What element is formed when neptunium atoms fall apart?
For the most common isotope of neptunium, Np-237, the decay daughter is protactinium-233.
Each isotope has another type of decay.
Uranium-238 undergoes nuclear decay Therefore uranium-238 will?
Become thorium-234 after ejecting an alpha particle and gamma ray.
The thorium-234 continues to decay through 13 more decay events, ultimately becoming lead-126.
What does americium taste like?
I am not sure whether anybody has actually tried tasting it, since that would be rather dangerous.
What is more radioactive than pure uranium?
Many radioactive isotopes are more radioactive than the naturally occurring uranium isotopes:
- All fission product isotopes are more radioactive (e.g. iodine-131, strontium-90)
- Most radioactive isotopes in the uranium --> lead decay chain are more radioactive (e.g. radium, radon, polonium)
- Plutonium is more radioactive
- Tritium is more radioactive
- Carbon-14 is more radioactive
- Artificially produced uranium isotopes are more radioactive (e.g. uranium-233, uranium-236)
- etc.
When an isotope is what it does not undergo radioactive decay?
friends are like seashells you collect on the way
What element used as shield for radioactivity?
It depends somewhat on the type of radiation that one needs to be shielded.
Lead is very effective for gamma rays, however if the radiation is mostly neutron radiation then borated reinforced concrete is much more effective than lead (the hydrogen in the water of crystallization in the concrete slows the neutrons and the boron then absorbs the slow neutrons). Nuclear reactors which produce intense radiation of both gamma ray and neutron often use alternating layers of lead plate and borated reinforced concrete for shielding.
If all you are shielding against is beta radiation then a sheet of aluminum foil is typically adequate.
If all you are shielding against is alpha radiation then your skin (do not ingest or inhale alpha emitters) or one sheet of paper is adequate.
Why do unstable nuclei undergo nuclear decay?
The simple answer is to release excess energy and thus become more stable.
The full answer requires some understanding of Quantum Mechanics, as it is a quantum process and even though an atom has excess energy to release its current state may be one that Quantum Mechanics prohibits (or encourages) certain changes from occurring.
How is half life used for carbon dating?
Knowing the half life of carbon-14 the age of an artefact containing an organic material can be evaluated.
What does an isotope release as a beta particle?
Usually when isotopes undergo beta decay they emit an electron, but some isotopes emit a positron instead. This depends on the relative number of neutrons to protons in the isotope which type of beta particle is emitted. An excess of neutrons leads to the emission of an electron, while an excess of protons leads to the emission of a positron.
Which statement describes the differences between chemical reactions and nuclear decay rates?
Nuclear decay rates vary, but chemical reaction rates are constant
What is the product of alpha decay for americium -241?
The intermediate product is neptunium 237 ( a very long-lived radioisotope).
Radioactive decay can be affected by?
The rate of decay of a radioactive element cannot be influenced by any physical or chemical change. It is a rather constant phenomenon that appears to be independent of all others. The rate of decay is given by an element's half life, which is the amount of time for approximately half of the atoms to decay.
What is the nuclear equation for the alpha decay of uranium 239?
Uranium-239 does NOT decay by alpha decay, it decays only by beta and gammadecay.
The most common is carbon 14.
