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Up to this point in your chemistry journey, you have learned about Chemical Reactions and how different compounds undergo different types of reactions to form products. Now, it is time to dive into a new type of reaction, which are reactions that happen in the nucleus! Nuclear reactions are extremely important in nuclear chemistry!
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Jetzt kostenlos anmeldenUp to this point in your chemistry journey, you have learned about Chemical Reactions and how different compounds undergo different types of reactions to form products. Now, it is time to dive into a new type of reaction, which are reactions that happen in the nucleus! Nuclear reactions are extremely important in nuclear chemistry!
Let's start by looking at the definition of nuclear chemistry. Nuclear chemistry is the chemistry that deals with radioactivity, nuclear reactions and nuclear properties.
Nuclear chemistry is a sub-field of chemistry that studies the changes that happen in the nucleus of elements.
Nuclear reactions are reactions that involve an atom's nucleus. Since the nucleus is comprised of nucleons, which are protons and neutrons, we tend to ignore electrons as they are not a part of the nucleus.
When dealing with nuclear chemistry, the atom is referred to as the nuclide.
A nuclide is a particular instance of an atom of an atomic nucleus, for example, \(^{16}_{8}\text{O}\), is a particular nucleus of oxygen.
Now, there are two ways to represent nuclides: atomic notation and mass notation. In atomic notation, the number on the top is the mass number, while the number on the bottom is the atomic number. In mass notation, the name of the element is followed by the mass number. For example, the atomic notation of an isotope of radium containing 140 neutrons is written as \( ^{228}_{88}\text{Ra} \), whereas its mass notation is radium-228,
Figure 1. Atomic notation of radioactive isotope of radium, Isadora Santos - StudySmarter Originals.
Isotopes are atoms of the same element containing the same number of protons, but varying numbers of neutrons in their nucleus. To learn more about radioisotopes, check out "Radioactive Isotopes"!
Now, let's dive into the history of nuclear chemistry and learn about three different chemists that were important in the discovery of radioactivity.
First up, we have Wilhelm Röntgen, a German physicist. Röntgen was interested in understanding how a Crookes tube worked. The Crookes tube was a device created in 1870 by a British scientist named William Crookes. It consisted of a sealed glass cylinder, with no oxygen inside and two electrodes (an anode and a cathode). When there was a high voltage difference between both electrodes, a green/yellow glow would appear behind the anode, as if this light was being emitted from the cathode. Physicists called this invisible light "cathode rays".
However, in 1895, Röntgen discovered that there was another unknown radiation being emitted by the Crookes tube, besides the cathode rays. Well, it turns out he had just discovered X-rays!
Then, in 1896, Henri Becquerel enters the picture. Becquerel used the newly discovered X-rays to do some experimentation, and by accident, he stumbled upon the discovery of phosphorescent uranium salts that spontaneously emitted radiation! Becquerel had just discovered a new phenomenon: radioactivity!
Marie Curie was also a pioneer of radioactivity. In 1898, together with her husband Pierre Curie, Marie Curie discovered the elements polonium and radium. Marie was also the one who coined the term radioactivity.
Radioactivity is referred to as the Spontaneous Decay (disintegration) of the nucleus of an unstable isotope.
The nuclear equations in nuclear chemistry involve special particles called nuclear particles, and the involvement of each of these nuclear particles depends on the type of nuclear decay happening to the nucleus of an unstable isotope.
Unstable isotopes (Radioactive Isotopes) are those that have an unstable nucleus that can spontaneously undergo radioactive decay to form a stable isotope (daughter isotope).
Nuclear decay (also known as radioactive decay) is the Spontaneous Decay (decomposition) of an unstable nucleus that leads to the formation of a stable nucleus (stable isotope). In this process, some mass gets converted into energy.
Most importantly, in nuclear decay, a radioactive isotope with an unstable nucleus (also known as the parent isotope) undergoes spontaneous decomposition of its nucleus to form a daughter isotope with a stable nucleus!
A daughter isotope (or daughter nuclide) is a stable isotope formed from the radioactive decay of the parent isotope containing an unstable nucleus.
There are six nuclear particles associated with nuclear equations. These are the neutron particle, proton particle, beta particle, alpha particle, and positron particle.
When nuclear decay happens, these nuclear particles are either emitted or absorbed. Now, let's explore the different types of radioactive decay and the nuclear particles involved!
Beta decay is probably the most common type of nuclear decay seen in nuclear reactions. In beta decay, an alpha particle (\(^{4}_{2}\alpha \)) is emitted, while the stable isotope loses one neutron and gains a proton.
Beta (β) decay is a radioactive decay that tend to occur in Radioactive Isotopes with a mass greater than the mass seen in the Periodic Table for that element.
For example, let's say that you have a radioactive isotope of carbon, carbon-14. The atomic notation for carbon-14 is \( ^{14}_6\text {C} \), meaning that has an atomic number of 6 and a mass number of 14.
Now, if you look for Carbon in your Periodic Table, you will find that the mass of carbon in the Periodic Table is 12. Since the mass number of carbon-14 is greater (14) than that mass number in the Periodic Table, carbon-14 will undergo beta decay.
$$ ^{14}_{6}\text{C }\longrightarrow \text{ }^{0}_{-1}\text{e + }^{14}_{7}\text{N} $$
Electron capture is basically the opposite of what we just saw in beta decay. During electron capture, a beta particle is absorbed instead of emitted.
Electron capture is a radioactive decay that tends to occur in radioactive isotopes with a mass smaller than the mass seen in the periodic table for that element
During electron capture, an electron in an atom's inner shell is drawn into the nucleus where it combines with a proton, forming a neutron and a neutrino. The neutrino is ejected from the atom's nucleus. The nuclear equation below shows the electron capture in 196Pb.
$$ ^{196}_{82}\text{Pb + } ^{0}_{-1}\text{e }\longrightarrow ^{196}_{81}\text{Tl + } \nu_{e} $$
Let's solve a problem!
What type of nuclear decay will the isotope \( ^{26}_{13} \text{Al} \) most likely undergo?
The first thing we need to do is look for Aluminum (Al) in the periodic table and compare their masses. In the periodic table, Aluminum (Al) has a mass of 29.982. So, since the mass of the isotope is smaller than the mass in the periodic table, \( ^{26} \text{Al} \) will most likely undergo electron capture!
$$ ^{26}_{13}\text{ Al}+\text{ } ^{0}_{-1}\beta\to \text{ }^{26}_{12}\text{ Mg} $$
Positron emission is a type of nuclear decay that can happen in isotopes with a mass smaller than that in the periodic table. In this case, a positron particle gets emitted, leading to the isotope gaining one neutron and losing one proton.
The nuclear equations for the positron emission in \( ^{26} \text{Al} \) is shown below:
$$ ^{26}_{13}\text{ Al }\to ^{0}_{1}\beta\text{ + }^{26}_{12}\text{ Mg } $$
The fourth type of nuclear decay is called alpha decay.
Alpha (α) decay is a radioactive decay that tend to occur in radioactive isotopes with an atomic number higher than 82.
In this case, an alpha particle (\( ^{4}_{2}\alpha \)) gets emitted, and the resulting isotope will lose two protons and two neutrons (the equivalent of a helium nucleus!).
$$ ^{238}_{92}\text{U }\to \text{ }^{234}_{90}\text{Th + } ^{4}_{2} \alpha $$
Interested in learning how to balance nuclear reactions? Check out "Balancing Nuclear Equations"!
Now that we know what nuclear chemistry encompasses and the different types of nuclear decay that can occur, let's look at some examples.
Plutonium-239 is a radioactive isotope of the element plutonium, and it is used in the generation of nuclear weapons. Since \( ^{239}_{94} \text {Pu}\) has an atomic number greater than 82 (94 > 82), its expected mode of decay is alpha decay.
$$ ^{239}_{94}\text{Pu }\to \text{ }^{235}_{92}\text{U + } ^{4}_{2} \alpha $$
Another example of an important radioactive isotope in nuclear chemistry is Fluorine-18. This isotope is important in positron emission tomography (PET), a type of imaging used to see the metabolic functions of tissues and organs. Fluorine-18 undergoes positron emission.
$$ ^{18}_{9}\text{ F }\to \text { } ^{0}_{1}\beta\text{ + }^{18}_{8}\text{O} $$
To finish off, let's talk explore the applications of nuclear chemistry. Nuclear chemistry has very important medical applications, as some radioactive isotopes can be used for imaging, and also in the process of diagnosis and cancer treatment. Samarium-153, for instance, is a radioisotope used in the treatment of bone cancer.
The figure below shows some common isotopes used in the diagnosis and treatment of certain diseases.
Now, I hope that you feel ready to dive deep into nuclear chemistry!
Nuclear chemistry is a sub-field of chemistry that studies the changes that happen in the nucleus of elements.
Nuclear chemistry is used in everyday life for diagnosis and treatment of cancer.
Nuclear chemistry is important because it deals with nuclear reactions and decay.
Nuclear chemistry has very important medical applications, as some radioactive isotopes can be used for imaging, and also in the process of diagnosis and cancer treatment. Samarium-153, for instance, is a radioisotope used in the treatment of bone cancer.
Stable isotopes will not undergo nuclear decay, whereas unstable isotopes will undergo decay and be considered radioactive.
Some benefits of nuclear chemistry include using radioactive isotopes for the dating of objects, and also in the diagnosis and treatment of diseases such as cancer.
The periodic table arranges elements according to their _______.
atomic number
The atomic number is the number of _____ that in the nucleus.
protons
The number of protons is also equal to the number of ______ the atom has when it is neutrally charged.
electrons
The atomic mass of an element is the average mass of all the average occurring _____ of that element.
isotopes
True or false: during nuclear reactions, mass is actually converted into large amounts of energy.
True
The proton particle contains a mass number of _____ and an atomic number of 1.
1
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