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Ch.21 - Transition Elements and Coordination Chemistry
All textbooksMcMurry 8th EditionCh.21 - Transition Elements and Coordination ChemistryProblem 1
Chapter 21, Problem 1

What is an absorption spectrum? If the absorption spectrum of a complex has just one band at 455 nm, what is the color of the complex?

Verified step by step guidance
1
Step 1: Understand the concept of an absorption spectrum. An absorption spectrum is a graph or a plot that shows the wavelengths of light absorbed by a substance. When light passes through a sample, certain wavelengths are absorbed by the electrons in the atoms or molecules, causing them to move to higher energy levels.
Step 2: Recognize that the absorption spectrum is related to the color of the substance. The color we perceive is due to the wavelengths of light that are not absorbed but instead transmitted or reflected. These are the complementary colors to those absorbed.
Step 3: Identify the wavelength of light absorbed by the complex. In this case, the complex absorbs light at 455 nm, which is in the blue region of the visible spectrum.
Step 4: Determine the complementary color to the absorbed wavelength. The complementary color to blue (around 455 nm) is orange. This is because the color wheel used in color theory shows that colors opposite each other are complementary.
Step 5: Conclude that the color of the complex is the complementary color to the absorbed wavelength. Since the complex absorbs blue light, it will appear orange to the human eye.

Key Concepts

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

Absorption Spectrum

An absorption spectrum is a graphical representation that shows the wavelengths of light absorbed by a substance. When light passes through a sample, certain wavelengths are absorbed by the electrons in the atoms or molecules, causing them to transition to higher energy levels. The resulting spectrum displays dark lines or bands at specific wavelengths, indicating the absorbed light, which can be used to identify the substance and its electronic structure.
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Color Perception

The color perceived by an observer is determined by the wavelengths of light that are not absorbed by a substance. When a complex absorbs light at a specific wavelength, the complementary color of that absorbed wavelength is what is observed. For example, if a complex absorbs light at 455 nm, which corresponds to blue light, the color perceived will be the complementary color, which is orange.
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Complementary Colors

Complementary colors are pairs of colors that, when combined, cancel each other out, resulting in a grayscale color like white or black. In the context of light absorption, the color that is observed is the complementary color of the absorbed wavelength. For instance, the color wheel shows that blue (around 455 nm) is complemented by orange, meaning if a complex absorbs blue light, it will appear orange to the observer.
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Related Practice
Textbook Question

What is the Lewis base in the reaction of oxalate with the mangenese ion to form [Mn(C2O4)3]2-? What is the oxidation state of Mn and the coordination number of the complex?  

(a) Lewis base is C2O42-; Mn oxidation number is +3; coordination number is 3.

(b) Lewis base is C2O42-; Mn oxidination number is +2; coordination number is 6.

(c) Lewis base is Mn2+; Mn oxidation number is +2; coordination number is 3.

(d) Lewis base is Mn4+; Mn oxidation number is +4; coordination number is 6.

Textbook Question

Refer to the figure showing the structure of various ligands to answer questions 4 and 5. Which ligand(s) can participate in linkage isomerism?

(a) All of the ligands can participate in linkage isomerism

(b) I, II, and III

(c) I and IV

(d) II and IV