Chapter 18: Problem 78
When a nucleus undergoes alpha decay, the ____________ of the nucleus decreases by four units.
Short Answer
Expert verified
When a nucleus undergoes alpha decay, the \(mass\:number\) of the nucleus decreases by four units.
Step by step solution
01
Understanding Alpha Decay
Alpha decay is a radioactive decay process where an unstable atomic nucleus loses two protons and two neutrons (An alpha particle - also known as a helium nucleus) to become a lighter nucleus.
02
Identifying the Property
When a nucleus loses two protons and two neutrons during alpha decay, the total number of protons and neutrons in the nucleus decreases. The sum of protons and neutrons in a nucleus is called its mass number (A). So, the property that decreases by four units during alpha decay is the mass number.
03
Filling in the Blank
Now that we know which property decreases by four units, we can fill in the blank in the given sentence: When a nucleus undergoes alpha decay, the mass number of the nucleus decreases by four units.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Radioactive Decay
Radioactive decay is a natural process by which an unstable atomic nucleus loses energy by emitting particles or radiation. This phenomenon is part of the spontaneous transformation that can alter both the number of protons and neutrons in the nucleus, leading to the formation of different elements or isotopes.
Alpha decay, one specific type of radioactive decay, involves the release of an alpha particle, which consists of two protons and two neutrons. The emission of an alpha particle from the nucleus results in a new element with an atomic number that is two less than the original and a mass number that decreases by four units. Throughout the decay process, energy is conserved by the emission of alpha particles at high speed, carrying kinetic energy away from the nucleus.
Alpha decay, one specific type of radioactive decay, involves the release of an alpha particle, which consists of two protons and two neutrons. The emission of an alpha particle from the nucleus results in a new element with an atomic number that is two less than the original and a mass number that decreases by four units. Throughout the decay process, energy is conserved by the emission of alpha particles at high speed, carrying kinetic energy away from the nucleus.
Significance in Nature and Applications
In nature, radioactive decay is responsible for the transformation of heavier unstable elements into more stable ones over time. This process is used to date geological formations and archeological artifacts through radiometric dating methods. Moreover, certain types of radioactive decay, including alpha decay, are harnessed in medical treatments, such as cancer radiotherapy, and as a power source in radioisotope thermoelectric generators.Mass Number
The mass number, represented by the letter 'A', is a fundamental property of atomic nuclei, denoting the total count of protons, which are positively charged particles, and neutrons, which are neutral particles. These two particle types are bound together within the atomic nucleus, providing the majority of an atom's mass.
When an atomic nucleus undergoes alpha decay, its mass number decreases because it loses an alpha particle containing two protons and two neutrons. The loss of these four particles means the mass number will reduce by four units. For example, if the initial mass number of an atom was 238, after alpha decay, the mass number would be 234.
When an atomic nucleus undergoes alpha decay, its mass number decreases because it loses an alpha particle containing two protons and two neutrons. The loss of these four particles means the mass number will reduce by four units. For example, if the initial mass number of an atom was 238, after alpha decay, the mass number would be 234.
Importance in Identifying Elements
The mass number is vital in identifying isotopes, as it differentiates atoms of the same element that have varying numbers of neutrons. While the chemical properties of isotopes are similar, their mass numbers lead to different physical properties, which can be essential for various scientific and industrial applications.Atomic Nucleus
The atomic nucleus is the small, dense region at the center of an atom where protons and neutrons are held together by the strong nuclear force. Despite its tiny volume relative to the entire atom, the nucleus contains almost all of an atom's mass since protons and neutrons are much heavier than electrons, which are distributed in electron shells around the nucleus.
The stability of an atomic nucleus depends on the balance between the number of protons and neutrons it contains. Unstable nuclei may undergo radioactive decay to reach a more stable configuration. The process of alpha decay, for example, is one way the nucleus can become more stable by shedding excess protons and neutrons.
The stability of an atomic nucleus depends on the balance between the number of protons and neutrons it contains. Unstable nuclei may undergo radioactive decay to reach a more stable configuration. The process of alpha decay, for example, is one way the nucleus can become more stable by shedding excess protons and neutrons.