Domanda del libro di testo
(b) X-ray diffraction studies of buckminsterfullerene show that it has a face-centered cubic lattice of C60 molecules. The length of an edge of the unit cell is 14.2 Å. Calculate the density of buckminsterfullerene.
Ch.12 - Solids and Modern Materials
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232
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TOC.tableOfContents
- Ch.1 - Introduction: Matter, Energy, and Measurement177
- Ch.2 - Atoms, Molecules, and Ions231
- Ch.3 - Chemical Reactions and Reaction Stoichiometry216
- Ch.4 - Reactions in Aqueous Solution189
- Ch.5 - Thermochemistry175
- Ch.6 - Electronic Structure of Atoms168
- Ch.7 - Periodic Properties of the Elements150
- Ch.8 - Basic Concepts of Chemical Bonding177
- Ch.9 - Molecular Geometry and Bonding Theories200
- Ch.10 - Gases179
- Ch.11 - Liquids and Intermolecular Forces113
- Ch.12 - Solids and Modern Materials154
- Ch.13 - Properties of Solutions157
- Ch.14 - Chemical Kinetics199
- Ch.15 - Chemical Equilibrium128
- Ch.16 - Acid-Base Equilibria164
- Ch.17 - Additional Aspects of Aqueous Equilibria163
- Ch.18 - Chemistry of the Environment105
- Ch.19 - Chemical Thermodynamics164
- Ch.20 - Electrochemistry171
- Ch.21 - Nuclear Chemistry122
- Ch.22 - Chemistry of the Nonmetals82
- Ch.23 - Transition Metals and Coordination Chemistry79
- Ch.24 - The Chemistry of Life: Organic and Biological Chemistry16
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Non è quello che usi tu?Cambia libro di testo
Capitolo 12, Problema 123
When you shine light of band gap energy or higher on a semiconductor and promote electrons from the valence band to the conduction band, do you expect the conductivity of the semiconductor to (a) remain unchanged, (b) increase, or (c) decrease?
Guida verificata passo dopo passo1
Step 1: Understand the structure of a semiconductor. Semiconductors have a valence band filled with electrons and a conduction band that is typically empty. The energy gap between these two bands is known as the band gap.
Step 2: Consider what happens when light with energy equal to or greater than the band gap is shone on the semiconductor. This energy can excite electrons from the valence band to the conduction band.
Step 3: Recognize that when electrons are promoted to the conduction band, they leave behind holes in the valence band. Both the electrons in the conduction band and the holes in the valence band can contribute to electrical conductivity.
Step 4: Analyze the effect of increased charge carriers. With more electrons in the conduction band and more holes in the valence band, the number of charge carriers increases, which typically enhances the material's ability to conduct electricity.
Step 5: Conclude that the conductivity of the semiconductor is expected to increase when light of band gap energy or higher is shone on it, due to the increased number of charge carriers.
Concetti chiave
Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.
Band Gap Energy
Band gap energy is the energy difference between the valence band, where electrons are normally present, and the conduction band, where electrons can move freely and contribute to electrical conductivity. In semiconductors, this gap is small enough that when energy, such as light, is applied, electrons can be excited from the valence band to the conduction band, allowing for increased conductivity.
Video consigliato:
Percorso guidato
03:13
Intepreting the Band of Stability
Electron Promotion
Electron promotion refers to the process of moving electrons from a lower energy state (valence band) to a higher energy state (conduction band) when sufficient energy is provided. This transition is crucial in semiconductors, as it directly affects their ability to conduct electricity. The promotion of electrons increases the number of charge carriers available for conduction, thereby enhancing the material's conductivity.
Video consigliato:
Percorso guidato
01:24Electron Configuration Exceptions Example
Conductivity in Semiconductors
Conductivity in semiconductors is a measure of how easily electric current can flow through the material. It is influenced by the number of charge carriers (electrons and holes) present. When light of sufficient energy is shone on a semiconductor, it promotes electrons to the conduction band, increasing the number of free charge carriers and thus raising the conductivity of the semiconductor.
Video consigliato:
Percorso guidato
01:40Extensive Property Example
Pratica correlata
Domanda del libro di testo
(a) The density of diamond is 3.5 g/cm3, and that of graphite is 2.3 g/cm3. Based on the structure of buckminsterfullerene, what would you expect its density to be relative to these other forms of carbon?
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Domanda del libro di testo
The karat scale used to describe gold alloys is based on mass percentages. (a) If an alloy is formed that is 50 mol% silver and 50 mol% gold, what is the karat number of the alloy? Use Figure 12.18 to estimate the color of this alloy.
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Domanda del libro di testo
The karat scale used to describe gold alloys is based on mass percentages. (b) If an alloy is formed that is 50 mol% copper and 50 mol% gold, what is the karat number of the alloy? What is the color of this alloy?
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