Textbook Question
Look at the location in the periodic table of elements A, B, C, and D. What is the electron configuration of the transition metal in each of the following ions?
(a) A2+
(b) B+
Ch.21 - Transition Elements and Coordination Chemistry
Chapter 21, Problem 21.38
Predict the number of unpaired electrons for each of the following.
(c) Zn2+
(d) Cr3+
Verified step by step guidance1
Determine the electron configuration of the neutral atom for each element.
For Zn, the electron configuration is [Ar] 3d^{10} 4s^2.
For Cr, the electron configuration is [Ar] 3d^5 4s^1.
Remove electrons according to the charge of the ion. For Zn^{2+}, remove 2 electrons from the 4s orbital. For Cr^{3+}, remove 3 electrons starting from the 4s orbital and then from the 3d orbital.
Count the number of unpaired electrons in the resulting electron configuration for each ion.
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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. Understanding the electron configuration of an element is crucial for predicting its chemical behavior, including the number of unpaired electrons.
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Electron Configuration Example
Unpaired Electrons
Unpaired electrons are those that occupy an orbital alone, without a paired electron of opposite spin. The presence of unpaired electrons is significant because it influences an atom's magnetic properties and reactivity. Atoms with unpaired electrons tend to be more reactive and can form bonds more readily.
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Transition Metals and Oxidation States
Transition metals can exhibit multiple oxidation states, which affect their electron configurations. For example, when transition metals lose electrons to form cations, the electrons are typically removed from the outermost s and d orbitals. Understanding how to determine the oxidation state of an element helps in predicting the resulting electron configuration and the number of unpaired electrons.
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Related Practice
Textbook Question
The oxalate ion is a bidentate ligand as indicated in Figure 21.8. Would you expect the carbonate ion to be a monodentate or bidentate ligand? Explain your reasoning.
Textbook Question
Classify the following ligands as monodentate, bidentate, tri-dentate, or tetradentate. Which can form chelate rings?
(a)
(b)
(c)
(d)
Textbook Question
Predict the number of unpaired electrons for each of the following.
(c) Mn3+
(d) Cr2+
Textbook Question
Predict the number of unpaired electrons for each of the following.
(a) Sc3+
(b) Co2+
Textbook Question
What is the general trend in standard potentials for the oxidation of first-series transition metals from Sc to Zn? What is the reason for the trend?