Textbook Question
The two most common isotopes of uranium are 235U and 238U. (b) Using the periodic table in the frontinside cover, write the electron configuration for a U atom.
Ch.6 - Electronic Structure of Atoms
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232
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Table of contents
- Ch.1 - Introduction: Matter, Energy, and Measurement177
- Ch.2 - Atoms, Molecules, and Ions231
- Ch.3 - Chemical Reactions and Reaction Stoichiometry216
- Ch.4 - Reactions in Aqueous Solution189
- Ch.5 - Thermochemistry175
- Ch.6 - Electronic Structure of Atoms168
- Ch.7 - Periodic Properties of the Elements150
- Ch.8 - Basic Concepts of Chemical Bonding177
- Ch.9 - Molecular Geometry and Bonding Theories200
- Ch.10 - Gases179
- Ch.11 - Liquids and Intermolecular Forces113
- Ch.12 - Solids and Modern Materials154
- Ch.13 - Properties of Solutions157
- Ch.14 - Chemical Kinetics199
- Ch.15 - Chemical Equilibrium128
- Ch.16 - Acid-Base Equilibria164
- Ch.17 - Additional Aspects of Aqueous Equilibria163
- Ch.18 - Chemistry of the Environment105
- Ch.19 - Chemical Thermodynamics164
- Ch.20 - Electrochemistry171
- Ch.21 - Nuclear Chemistry122
- Ch.22 - Chemistry of the Nonmetals82
- Ch.23 - Transition Metals and Coordination Chemistry79
- Ch.24 - The Chemistry of Life: Organic and Biological Chemistry16
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Not the one you use?Change textbook
Chapter 6, Problem 110d
The two most common isotopes of uranium are 235U and 238U. (d) 238U undergoes radioactive decay to 234Th. How many protons, electrons, and neutrons are gained or lost by the 238U atom during this process? (e) Examine the electron configuration for Th in Figure 6.31. Are you surprised by what you find? Explain.
Verified step by step guidance1
Identify the atomic numbers and mass numbers of the isotopes involved. Uranium-238 (238U) has an atomic number of 92 and a mass number of 238. Thorium-234 (234Th) has an atomic number of 90 and a mass number of 234.
Determine the change in the number of protons during the decay process. Since the atomic number decreases from 92 (Uranium) to 90 (Thorium), two protons are lost.
Analyze the change in the number of neutrons. Neutrons can be calculated by subtracting the atomic number from the mass number. For 238U, it has 238 - 92 = 146 neutrons, and for 234Th, it has 234 - 90 = 144 neutrons. Thus, two neutrons are lost.
Consider the change in the number of electrons. Since the atom remains neutral throughout the decay, and two protons are lost, two electrons are also lost to maintain charge neutrality.
Examine the electron configuration of Thorium as shown in the referenced figure to understand any peculiarities or expected configurations, especially in comparison to its position in the periodic table and its expected electron configuration based on its atomic number.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Isotopes
Isotopes are variants of a chemical element that have the same number of protons but different numbers of neutrons. For example, uranium-235 (235U) and uranium-238 (238U) are isotopes of uranium, with 235U having 143 neutrons and 238U having 146 neutrons. This difference in neutron count affects their stability and radioactive properties.
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Isotopes
Radioactive Decay
Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting radiation. In the case of 238U decaying to 234Th, it undergoes alpha decay, where it emits an alpha particle (2 protons and 2 neutrons). This process changes the element into a different one, resulting in a loss of protons and neutrons from the original atom.
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Electron Configuration
Electron configuration describes the distribution of electrons in an atom's orbitals. It is crucial for understanding an element's chemical properties and reactivity. For thorium (Th), the electron configuration can reveal its valence electrons and how it might bond with other elements, which can be surprising if it differs significantly from its predecessor in the decay process.
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Related Practice
Textbook Question
(d) Treating bismuth with fluorine gas forms BiF5. Use the electron configuration of Bi to explain the formation of a compound with this formulation.
Textbook Question
The first 25 years of the twentieth century were momentous for the rapid pace of change in scientists' understanding of the nature of matter. (b) In what ways is de Broglie's hypothesis, as it applies to electrons, consistent with J. J. Thomson's conclusion that the electron has mass? In what sense is it consistent with proposals preceding Thomson's work that the cathode rays are a wave phenomenon?