Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 20: Problem 24

What is the origin of color in a compound?

Short Answer

Expert verified
The color of a compound originates from the absorption of light whose frequency corresponds to the energy difference between two quantum states of a molecule. The absorbed light leads to an electron transition that characterizes the color we perceive.

Step by step solution

01

Understanding Light Absorption

Light is absorbed by compounds when it has a particular frequency (or, equivalently, wavelength) that corresponds to the energy difference between two quantum states of the molecules. The individual 'packets' of light (known as photons) promote an electron from a lower energy level to a higher level.
02

Role of the Electron

The electron absorbs the energy of the photon, and moves to a higher energy level. This absorption of energy characterizes the color that we perceive.
03

Transition of Electron and Color Perception

When light is shone on a compound, it may absorb certain wavelengths (energies), corresponding to the energy difference between allowed electron transitions. If a compound absorbs certain colors from white light (for example, blue and green), the colors that are not absorbed are transmitted, and this transmitted light is what we see. So, if a compound absorbs blue and green light, the light transmitted and observed would be the complementary color (in this case, red).
04

The energy differences and the colors

If the energy difference between the electron states fits the energy of a (visible) photon, the photon can be absorbed lifting an electron up from the lower to the upper state. The energy of a photon and hence its color depends on the wavelength \(\lambda\): \(E=hc/ \lambda\) where \(h\) is Planck's constant and \(c\) is the speed of light. Different compounds have different energy levels and transitions, and so will absorb (and transmit) different colors.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Aqueous copper(II) sulfate solution is blue in color. When aqueous potassium fluoride is added, a green precipitate is formed. When aqueous potassium chloride is added instead, a bright-green solution is formed. Explain what is happening in these two cases.

How many geometric isomers are in these species: (a) \(\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{2} \mathrm{Cl}_{4}\right]^{-},(\mathrm{b})\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{3} \mathrm{Cl}_{3}\right] ?\)

Write the formulas for each of these ions and compounds: (a) tetrahydroxozincate(II), (b) pentaaquochlorochromium(III) chloride, (c) tetrabromocuprate(II), (d) ethylenediaminetetraacetatoferrate(II).

Predict the number of unpaired electrons in these complex ions: (a) \(\left[\mathrm{Cr}(\mathrm{CN})_{6}\right]^{4-}(\mathrm{b})\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}\)

Explain why atomic radii decrease very gradually from scandium to copper.
See all solutions

Recommended explanations on Chemistry Textbooks

Physical Chemistry

Read Explanation

Chemical Reactions

Read Explanation

Chemistry Branches

Read Explanation

Ionic and Molecular Compounds

Read Explanation

Nuclear Chemistry

Read Explanation

Organic Chemistry

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free