Electron Capture & Positron Emission: Study with Video Lessons, Practice Problems & Examples

Electron capture and positron emission are processes that unstable nuclei undergo to attain stability by balancing the number of protons and neutrons. In electron capture, an electron is absorbed by the nucleus, combining with a proton to form a neutron, thus reducing the proton count. For instance, cesium-131 absorbs an electron to become xenon-131. Positron emission involves a proton transforming into a neutron and emitting a positron, an antiparticle of the electron, which has no mass number and a positive charge. This process also decreases the number of protons, as seen when cesium-130 emits a positron to become xenon-130. Both processes are crucial for stabilizing nuclei with an excess of protons, ensuring mass and atomic numbers remain consistent before and after the transformation.

Electron Capture

Now electron capture is when an unstable nucleus captures or absorbs an electron from the inner electron orbital. Now here we're going to say this occurs in nuclei with an excess number of protons, so they would undergo electron capture to help us reduce the number of protons we're as helping to increase the number of neutrons.

Here we're going to say that a proton and electron combined together to help us give us a neutron. So by creating this neutron will actually bring down the number of protons, bringing them more in line with one another in terms of balance. Now here we have cesium 131. It's undergoing electron capture, meaning it's absorbing this electron.

Remember that your mass number on both sides have to be the same, and your total number of protons on both sides have to be the same. Here we have 131 + 0 = 131, 55 - 1 = 54. If we look on the periodic table, the only element with an atomic number of 54 would be xenon. So here we'd say that Susskind 131 undergoes electron capture, and in the process it produces Xenon 131 as a product.

Positron Emission

Now under positron emission, we're going to say that an unstable nucleus emits a positron particle. The positron particle itself can be seen as an antiparticle of the electron and because of this it symbolized as 0. So it has no mass number. Just like an electron it is an anti electron particle so it's still E but here it's anti because its symbol is positive instead of negative.

Now when a positron and an electron particles collide, so opposites of each other both are annihilated to form 2 gamma rays. Now this occurs in nuclei with excess number of protons, and just like with electron capture, it's going to help to decrease the number of protons in order to increase our number of neutrons. Here under the polytron emission, we're going to say that a proton splits into a neutron and a positron and that's how we're going to limit the number of protons since we have an excess of them and help to increase the number of neutrons.

Here we have cesium 130, cesium 130. It's going to do positive chronic mission. So here is our positron here, Remember your mass numbers have to be the same on both sides. Here we're going to say that this is still 130. The number of protons have to be the same on both sides. So this is 55 on the reactant side. So we need 55 on the product side. One of them is coming from a positron, so we need 54 more. So here we have 54 which would give us Xenon. So here we've just made Xenon 130 by way of positron emission from cesium 130.

Electron Capture & Positron Emission Example

Here we're told to write a nuclear reaction for each, and the first one we need to show electron capture of Iridium 189. So Iridium 189. Iridium has an atomic number of 77. Now Iridium is one of my favorite elements, so people theorize that the dinosaurs became extinct because a meteor crash landed into Earth and extinguished all of them. Now there's a scar in the Gulf of Mexico and if you were to go there and collect samples from that spot, you would see that it's composed of Iridium. Iridium comes from space, from stars. So it's one of my favorite elements because that little bit of trivia.

So here we have Iridium 189. It's undergoing electronic capture, so that means it's going to absorb an electronic. So our mass numbers need to be the same overall on the product side. So 189 + 0 is 189. The number of protons have to be the same on both sides, so this is 77 -. 1 gives us 76. So here this would change into osmium another one of my favorite elements because it's one of the most dense elements that exist on earth.

Ir 189 + e 0 → Os 189

So now B we need to positron emission of you uranium 229. So we have two 29 uranium which has an atomic number of 92 positron in Michigan. Emissions means it's a product. A positron is the anti electron so it's a positive electron and here we have 229 LUS 0 is 229. So mass numbers are the same on both sides. On the reactant side we have 92 protons. On the product side we need 92 protons we have plus one, which would mean we need 91 more and that would give me Pennsylvania as my isotope.

U 229 → Pa 229 + e 0

So these will represent our electron capture of Iridium 189 and positron emission of Uranium 229.

Provide a daughter nuclide when Rn-215 undergoes 2 sets of alpha decay and a positron emission.

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• B.
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Identify the missing species from the following nuclear reaction.

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• D.

Here’s what students ask on this topic:

What is electron capture?

Electron capture is a process in which an atomic nucleus absorbs one of the atom's own inner orbital electrons, causing a proton to convert into a neutron. This transformation results in the emission of an electron neutrino, which is a nearly massless particle that carries away some of the energy from the reaction. Electron capture is a type of beta decay, specifically ⁺ decay, because it effectively transforms a nuclear proton into a neutron and a positron (the antiparticle of the electron), with the positron immediately annihilating with the captured electron.

Electron capture is an important process in the universe, playing a role in the life cycle of stars and the formation of different isotopes. In the laboratory, it is used to study the properties of neutrinos and to understand nuclear structure. It also has practical applications in medicine, for example, in some types of diagnostic imaging where isotopes produced by electron capture are used.

In an electron capture process, which of the following occurs?

In an electron capture process, an inner orbital electron is captured by the nucleus of its own atom. This typically involves an electron from the K-shell (closest to the nucleus) being absorbed by a proton in the nucleus, which then transforms into a neutron. As a result of this process, the atomic number of the element decreases by one, effectively changing the element into a different isotope or even a different element altogether. Additionally, the capture of the electron usually leads to the emission of an X-ray and/or an Auger electron, as the electron cloud reorganizes to fill the vacancy left by the captured electron. This process is one of the modes of radioactive decay and is a way that atoms with a proton-rich nucleus can move towards a more stable configuration.

What is positron emission?

Positron emission is a type of radioactive decay, which is a process that unstable atoms can use to become more stable. In positron emission, a proton inside the nucleus of an unstable atom is transformed into a neutron. During this process, the proton emits a positron, which is a particle with the same mass as an electron but with a positive charge, and a neutrino, which is a very light, neutral particle that barely interacts with matter.

The emitted positron soon encounters an electron, and when they meet, they annihilate each other in a process called annihilation. This results in the release of energy in the form of gamma rays. Positron emission is important in the field of medical imaging, particularly in positron emission tomography (PET) scans, which use the emitted positrons to produce detailed images of the inside of the human body, helping in the diagnosis and treatment of various conditions.

Which of the following occurs during positron emission?

During positron emission, a proton inside an atom's nucleus is transformed into a neutron. In the process, the atom emits a positron, which is a particle with the same mass as an electron but with a positive charge, and a neutrino, which is a very light, neutral particle. This process decreases the atomic number of the element by one while keeping the mass number the same.

Positron emission is a type of beta decay, specifically beta-plus (_β⁺) decay. It is a phenomenon observed in proton-rich unstable nuclei. When a proton becomes a neutron, a positron is emitted to conserve the charge balance. The emitted positron will eventually collide with an electron, leading to a process called electron-positron annihilation, which results in the production of gamma-ray photons. This type of decay is used in medical imaging, such as positron emission tomography (PET) scans, to detect activity within the body at a molecular level.

Which nuclear equation is an example of positron emission?

Positron emission is a type of radioactive decay in which a proton in an atom's nucleus is converted into a neutron and a positron, and the positron is then emitted from the nucleus. The positron is the antiparticle of the electron, with the same mass but a positive charge. An example of a nuclear equation representing positron emission is the decay of carbon-11 into boron-11:

$C^{11}\to B^{11}+e^{+}+{\nu }_e$

In this equation, a carbon-11 nucleus (with 6 protons and 5 neutrons) emits a positron (denoted by $e^{+}$) and a neutrino (${\nu }_e$), resulting in a boron-11 nucleus (with 5 protons and 6 neutrons). The atomic number decreases by one (from 6 to 5) due to the loss of a proton, but the mass number remains the same because a neutron is left behind in the nucleus.