Solid State Chemistry Lecture 8 Quiz
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Questions and Answers

What will be discussed in lecture eight of the solid state chemistry course?

  • Molecular bonding principles
  • X-ray diffraction techniques
  • Electronic properties of materials (correct)
  • Thermodynamics and its applications

Insulators have high conductance.

False (B)

What is the most common type of X-ray source mentioned in the lecture?

X-ray anode

Electrons are accelerated towards the anode where they will hit a __________ material.

<p>target</p> Signup and view all the answers

Match the following materials with their electrical behavior:

<p>Conductors = High conductivity Semiconductors = Intermediate conductivity Insulators = Low conductivity</p> Signup and view all the answers

What theory will be introduced to understand the properties of solids?

<p>Band Theory (D)</p> Signup and view all the answers

The workshop sheet will be available one week before the workshop.

<p>True (A)</p> Signup and view all the answers

What does the linear combination of atomic orbitals help to extend into?

<p>solids</p> Signup and view all the answers

Which type of compounds typically have very high melting temperatures?

<p>Ionic compounds (D)</p> Signup and view all the answers

The first nano scale industry was pigmenting stained glass windows using gold nanoparticles.

<p>True (A)</p> Signup and view all the answers

What is the significance of optical properties in materials?

<p>Optical properties relate to electronic properties and are essential for applications like pigmentation.</p> Signup and view all the answers

In addition to being transparent, materials for photovoltaics must also be _____ to make efficient solar cells.

<p>conducting</p> Signup and view all the answers

Match the following types of materials with their properties:

<p>Ionic compounds = High melting temperatures Metallic compounds = Wide range of melting temperatures Covalent compounds = Also high melting temperatures Gold nanoparticles = Used in pigmentation</p> Signup and view all the answers

What type of light can synchrotron sources emit?

<p>Monochromatic light (C)</p> Signup and view all the answers

What challenges are associated with creating materials that are both transparent and conducting?

<p>Developing these materials is technically challenging. (B)</p> Signup and view all the answers

Synchrotron light sources operate by emitting light from atomic species only.

<p>False (B)</p> Signup and view all the answers

Pigmentation has been a non-essential aspect of industries throughout history.

<p>False (B)</p> Signup and view all the answers

What is the typical speed range of electrons used in synchrotron light sources?

<p>99.999% the speed of light</p> Signup and view all the answers

Why is transparency important for mobile phone screens?

<p>To allow users to see the display clearly while protecting it from the environment.</p> Signup and view all the answers

Synchrotron sources allow researchers to select the specific energy they want for their experiments by using ______.

<p>monochromators</p> Signup and view all the answers

Match the following materials with their characteristics:

<p>Metallic compounds = Malleable Ionic compounds = Stiff and fragile Covalent materials = Very hard Van der Waals materials = Flaky components</p> Signup and view all the answers

Which property is characteristic of covalent materials?

<p>Stiffness (C)</p> Signup and view all the answers

What happens to the conductivity of semiconductors as temperature increases?

<p>It increases. (A)</p> Signup and view all the answers

The use of diffraction materials is optional in synchrotron light sources for selecting energies.

<p>False (B)</p> Signup and view all the answers

Conductors have higher conductivity than insulators even at low temperatures.

<p>True (A)</p> Signup and view all the answers

Describe the effect of the speed of electrons in synchrotron light sources on the light produced.

<p>It generates far more intense and brilliant light.</p> Signup and view all the answers

What is the conductivity measure that indicates an insulator?

<p>Less than ten to the minus four Siemens per metre.</p> Signup and view all the answers

An insulator can be turned into a ________ by increasing the temperature.

<p>semiconductor</p> Signup and view all the answers

Match the following terms with their definitions:

<p>Conductor = Material with high conductivity at any temperature Insulator = Material with very low conductivity Semiconductor = Material that can conduct electricity under certain conditions Temperature effect = In semiconductors, conductivity increases with temperature</p> Signup and view all the answers

Which of the following statements is true about insulators?

<p>Their conductivity is almost immeasurable under normal conditions. (B)</p> Signup and view all the answers

Applying a bias to a semiconductor results in no electron movement.

<p>False (B)</p> Signup and view all the answers

What is the term used for the electronic bands in solid materials?

<p>Band theory.</p> Signup and view all the answers

What is the term for the maximum energy that an electron can have at zero Kelvin in a solid?

<p>Fermi energy (A), Fermi level (B)</p> Signup and view all the answers

When bands are half-filled, they exhibit a higher density of states due to the spread over a larger energy range.

<p>False (B)</p> Signup and view all the answers

What happens to the energy states and electron filling when new bands form from completely empty s orbitals?

<p>The newly forming s band will also be completely empty.</p> Signup and view all the answers

The energy states are bound or __________ from the ionic core.

<p>unbound</p> Signup and view all the answers

At what temperature is the Fermi energy typically referenced?

<p>Absolute zero (0 Kelvin) (A)</p> Signup and view all the answers

The Fermi level is often set to zero on the energy scale.

<p>True (A)</p> Signup and view all the answers

Electrons fill the orbitals from the __________ energy upwards.

<p>lowest</p> Signup and view all the answers

Which of the following materials is classified as an insulator?

<p>Diamond (B)</p> Signup and view all the answers

Silicon and germanium each have six valence electrons.

<p>False (B)</p> Signup and view all the answers

What is the typical band gap for semiconductors?

<p>Under about 1 eV</p> Signup and view all the answers

In a covalent compound, the bonding orbitals are found in the __________ band.

<p>valence</p> Signup and view all the answers

Match the following materials with their classification:

<p>Diamond = Insulator Silicon = Semiconductor Tin = Conductive material Germanium = Semiconductor</p> Signup and view all the answers

What happens when the energy difference between the antibonding and bonding orbitals is large?

<p>They result in a larger band gap. (A)</p> Signup and view all the answers

In semiconductors, the probability of an electron hopping across the band gap increases with increasing band gap size.

<p>False (B)</p> Signup and view all the answers

What defines the difference between a semiconductor and an insulator?

<p>The size of the band gap.</p> Signup and view all the answers

Flashcards

Conductor

A material that allows electric current to flow easily through it.

Semiconductor

A material that has a limited ability to conduct electricity, somewhere between a conductor and an insulator.

Insulator

A material that strongly resists the flow of electric current.

Band Theory

The theory that describes how electrons behave in solids and explains their conductivity.

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Linear Combination of Atomic Orbitals (LCAO)

A process where atomic orbitals combine to form molecular orbitals, spanning the entire solid.

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X-ray Anode

A common type of X-ray source that uses a heated filament to emit electrons.

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X-ray Emission Lines

The process of emitting light with a specific energy when an electron from a higher energy level transitions to a lower one.

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Core Levels

The energy levels that electrons occupy in an atom.

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Synchrotron Light Source

A type of light source that uses oscillating electrons to generate intense X-rays, allowing for a wider range of experiments.

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Monochromatization

The process of selecting a specific wavelength or energy of light, often used in synchrotron light sources.

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Malleable

A material that can be bent or deformed without breaking.

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Fragile

A material that is brittle and can easily break under stress.

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Van der Waals Materials

Materials that are held together by weak van der Waals forces, often having a layered or flaky structure.

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Hard

A material that resists scratching, indentation, or abrasion.

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Covalent Material

A material held together by strong covalent bonds, resulting in high stiffness and strength.

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Electronic Properties

The study of how electrons behave in materials, influencing their electrical and optical properties.

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Band Gap

The energy difference between the highest occupied energy level (valence band) and the lowest unoccupied energy level (conduction band) in a material.

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Valence Band

The energy level where electrons are tightly bound to atoms and responsible for holding the material together. It is usually filled with electrons.

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Conduction Band

The energy level where electrons are free to move and contribute to electrical conductivity. It is usually empty.

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Optical Properties

The ability of a material to absorb and transmit light, affecting its color and transparency.

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Pigmentation

The use of materials to create colors, particularly in pigments and dyes.

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Nanoparticles

Tiny particles of a material, typically on the scale of nanometers.

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Photovoltaics

The use of materials to convert light energy into electricity, as in solar cells.

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Transparent and Conducting Material

A material that allows both light and electricity to pass through it.

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Optical Properties and Electronic Properties

The relationship between a material's optical properties and its electronic structure, where how light interacts with the material is determined by how electrons behave.

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Gold Nanoparticle Pigmentation

The first industrial application of nano-scale materials, using gold nanoparticles to create colorful stained glass windows.

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Temperature dependence of semiconductors

The conductivity of a material increases with increasing temperature.

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Electronic Bands

The range of energy levels that electrons can occupy in a solid material.

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Atomic Orbitals

Individual atomic orbitals that are localized around their specific atoms.

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Fermi Level

The highest energy level an electron can occupy at absolute zero (0 Kelvin).

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Fermi Energy

The energy associated with the Fermi level. It represents the maximum energy an electron can have at 0 Kelvin.

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Binding Energy

The difference between the Fermi energy and the energy level associated with bound electrons, often representing the minimum energy required to remove an electron from a material.

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Density of States

A measure of how many electronic states exist within a given energy range in a material.

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Energy Bands

A range of energy levels that electrons can occupy in a material. These bands can be completely full, partially full, or empty.

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Filling of Energy Levels

Describes the filling of energy levels. Lower energy levels are filled first, followed by progressively higher levels.

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Energy Band Diagram

A diagram representing energy band structure, showing the spread of energy levels within a material and their occupancy by electrons.

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Pauli Exclusion Principle

The Pauli exclusion principle, which states that no two electrons in an atom can have the same quantum numbers, and therefore no two electrons can occupy the same atomic orbital. This limits the number of electrons that can occupy a specific energy level.

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Study Notes

Workshop Announcements

  • Tutorial workshop yesterday's lecture, online worksheet due next Wednesday
  • Online workshop sheets for chemistry workshops in two weeks
  • Thermodynamics workshop in two weeks' time

Lecture 8: Solid State Chemistry

  • Electronic structure of materials discussed: conductance and resistance
  • Band theory for understanding solids introduced
  • Linear combination of atomic orbitals for solids
  • Distinction between conductors, semiconductors, and insulators
  • X-ray anode discussed as a common X-ray source in labs and airports
  • Synchrotron light sources explained: far more intense light, wider range of experiment
  • Monochromatic light selection using diffraction methods in synchrotons
  • Electronic properties of materials discussed

Electronic Properties

  • Resistivity and conductivity are material properties.
  • Specific Materials have differing levels of resistivity and conductivity.
  • Resistivity and conductivity are directly related and the inversely proportional to each other
  • Length and cross-sectional area of a wire affect its resistance
  • Resistence is measured in Ohms, while conductance is measured in Siemens
  • Increasing temperature reduces conductivity in conductors
  • Increasing temperature increases conductivity in semiconductors

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Chem 2017 Solid State Chemistry Lecture Notes PDF

Description

Test your understanding of the electronic structure of materials covered in Lecture 8 of Solid State Chemistry. This quiz includes topics such as band theory, conductors, semiconductors, and insulators, as well as the practical applications of X-ray sources and synchrotron light. Challenge yourself and see how well you know these crucial concepts!

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