Skip to main content
Ch.21 - Transition Elements and Coordination Chemistry
McMurry - Chemistry 8th Edition
McMurry8th EditionChemistryISBN: 9781292336145Not the one you use?Change textbook
All textbooksMcMurry 8th EditionCh.21 - Transition Elements and Coordination ChemistryProblem 21.39
Chapter 21, Problem 21.39

Predict the number of unpaired electrons for each of the following. 
(a) Sc3+
(b) Co2+

Verified step by step guidance
1
Determine the electron configuration of the neutral atom for each element.
For Scandium (Sc), the atomic number is 21, so the electron configuration is [Ar] 3d^1 4s^2.
For Cobalt (Co), the atomic number is 27, so the electron configuration is [Ar] 3d^7 4s^2.
Remove electrons according to the charge of the ion. For Sc^3+, remove three electrons from the outermost orbitals, resulting in [Ar].
For Co^2+, remove two electrons from the outermost orbitals, resulting in [Ar] 3d^7. Determine the number of unpaired electrons in the 3d subshell.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Was this helpful?

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 lower-energy orbitals first. Understanding the electron configuration of an element is crucial for predicting its chemical behavior, including the number of unpaired electrons.
Recommended video:
Guided course
01:33
Electron Configuration Example

Unpaired Electrons

Unpaired electrons are those that occupy an orbital alone, without a partner of opposite spin. The presence of unpaired electrons in an atom influences its magnetic properties and reactivity. Atoms with unpaired electrons are often paramagnetic, while those with all electrons paired are diamagnetic.

Transition Metals and Oxidation States

Transition metals can exhibit multiple oxidation states due to their ability to lose different numbers of d electrons. The oxidation state affects the electron configuration and, consequently, the number of unpaired electrons. For example, Scandium (Sc) in the +3 oxidation state loses three electrons, while Cobalt (Co) in the +2 state loses two, altering their electron configurations.
Recommended video:
Guided course
03:12
Transition Metals
Related Practice
Textbook Question

What is the highest oxidation state for each of the elements from Sc to Zn?

101
views
Textbook Question

What is the oxidation state of the metal in each of the complexes?

a. AgCl2–

b. [Cr(H2O)5Cl]2+

c. [Co(NCS)4]2–

d. [ZrF8]4–

e. [Fe(EDTA)(H2O)]–

89
views
Textbook Question

The glycinate anion, gly-= NH2CH2CO2 -, bonds to metal ions through the N atom and one of the O atoms. Using to represent gly-, sketch the structures of the four stereoisomers of Co(gly)3.

134
views
Textbook Question

What role does EDTA4- play as a trace additive to mayonnaise? Would the glycinate ion (H2NCH2CH2NH2) be an effective substitute for EDTA4-?

71
views
Textbook Question

What hybrid orbitals are used by the metal ion and how many unpaired electrons are present the complex ion [VCl4]- with tetrahedral geometry?

(a) sp3; 2 unpaired electrons

(b) sp3; 3 unpaired electrons

(c) sp3d2; 3 unpaired electrons

(d) sp3d2; 4 unpaired electrons

88
views
Textbook Question

Which of the following complexes can exist as enantiomers? Draw their structures.

(a) [Cr(en)3]3+

(b) cis-[Co(NH3)Cl]2+

(c) trans-[Co(en)2(NH3)Cl]2+

(d) [Pt(NH3)3Cl3]+

112
views