Textbook Question
Write out the ground-state electron configurations of b. Ru²⁺
24. Transition Metals and Coordination Compounds
Electron Configurations of Transition Metals: Exceptions
Problem 37b
Textbook Question
Specify the electron configuration for each of the following atoms and ions.
(c) Cr(III) in Cr2O42-
(d) Cr(VI) in Cr2O72-
Verified step by step guidance1
Understand the oxidation states: Cr(III) means chromium is in the +3 oxidation state, and Cr(VI) means chromium is in the +6 oxidation state.
Determine the electron configuration of a neutral chromium atom: Chromium (Cr) has an atomic number of 24, so its electron configuration is [Ar] 3d^5 4s^1.
For Cr(III) in Cr2O4^2-: Remove 3 electrons from the neutral Cr configuration. Electrons are removed first from the 4s orbital, then from the 3d orbital.
For Cr(VI) in Cr2O7^2-: Remove 6 electrons from the neutral Cr configuration. Again, remove electrons first from the 4s orbital, then from the 3d orbital.
Write the final electron configurations for Cr(III) and Cr(VI) after removing the appropriate number of electrons.
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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 or ion's atomic orbitals. It follows the Aufbau principle, which states that electrons fill orbitals starting from the lowest energy level to the highest. Understanding how to write electron configurations is essential for predicting chemical behavior and reactivity.
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Oxidation States
Oxidation states indicate the degree of oxidation of an atom in a compound, reflecting the number of electrons lost or gained. In the case of chromium in Cr(III) and Cr(VI), the oxidation states are +3 and +6, respectively. This concept is crucial for determining the electron configuration of ions, as it affects the number of electrons present.
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Ionic vs. Atomic Electron Configuration
The electron configuration of ions differs from that of neutral atoms due to the loss or gain of electrons. For example, Cr(III) has lost three electrons compared to neutral chromium, while Cr(VI) has lost six. Recognizing this distinction is vital for accurately determining the electron configurations of the specified ions in the question.
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