Ch.6 - Electronic Structure of Atoms

Problem 110b

Chapter 6, Problem 110b

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.

Verified step by step guidance

Identify the atomic number of Uranium (U) from the periodic table, which tells you the number of protons and electrons in a neutral atom.

Understand that the electron configuration of an atom describes the distribution of electrons in the atomic orbitals. The configuration is built by adding electrons to the lowest energy orbitals first, following the Aufbau principle, Pauli exclusion principle, and Hund's rule.

Start filling the electrons into the orbitals from the lowest energy level to higher, following the order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f.

For Uranium, with an atomic number of 92, fill the electrons up to the 7s orbital. Remember that the f-orbitals start filling after the 6s orbital, and the d-orbitals are filled after the corresponding s-orbital except for the first row of the d-block.

Write the complete electron configuration by counting the electrons in each subshell until you reach a total of 92 electrons. The configuration will include the filling of the 5f and 6d orbitals.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Electron Configuration

Electron configuration describes the distribution of electrons in an atom's orbitals. It follows the Aufbau principle, which states that electrons fill the lowest energy orbitals first, and is typically represented using a notation that indicates the energy levels and sublevels occupied by electrons.

Periodic Table

The periodic table organizes elements based on their atomic number and electron configurations. It provides essential information about the elements, including their group and period, which helps predict their chemical behavior and the arrangement of their electrons.

Uranium Isotopes

Uranium has several isotopes, with 235U and 238U being the most common. Isotopes are variants of an element that have the same number of protons but different numbers of neutrons, affecting their nuclear properties but not their electron configuration, which is determined solely by the number of protons.

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Isotopes

Related Practice

Textbook Question

The discovery of hafnium, element number 72, provided a controversial episode in chemistry. G. Urbain, a French chemist, claimed in 1911 to have isolated an element number 72 from a sample of rare earth (elements 58–71) compounds. However, Niels Bohr believed that hafnium was more likely to be found along with zirconium than with the rare earths. D. Coster and G. von Hevesy, working in Bohr’s laboratory in Copenhagen, showed in 1922 that element 72 was present in a sample of Norwegian zircon, an ore of zirconium. (The name hafnium comes from the Latin name for Copenhagen, Hafnia). (c) Solid zirconium dioxide, ZrO₂, reacts with chlorine gas in the presence of carbon. Starting with a 55.4-g sample of ZrO₂, calculate the mass of ZrCl₄ formed, assuming that ZrO₂ is the limiting reagent and assuming 100% yield.

Open Question

(c) Consider the metal oxides whose enthalpies of formation (in kJ mol⁻¹) are listed here: Oxide K₂O₍s₂₎, CaO₍s₂₎, TiO₂₍s₂₎, V₂O₅₍s₂₎, ΔHf° -363.2, -635.1, -938.7, -1550.6. Calculate the enthalpy changes in the following general reaction for each case: MnOm₍s₂₎ + H₂(g) → nM₍s₂₎ + mH₂O(g). (You will need to write the balanced equation for each case and then compute ΔH°.)

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?

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Textbook Question

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.

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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.

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