Solid State Physics Basics Quiz

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Questions and Answers

What is the main premise of the quote from Edward Robert Harrison in the first paragraph?

The main premise of the quote is that the universe consists only of atoms and the void, and that all else is opinion and illusion.

What did Gerd Binnig and Heinrich Rohrer win the Nobel Prize in 1986 for?

Gerd Binnig and Heinrich Rohrer won the Nobel Prize in 1986 for the invention of the Scanning Tunneling Microscope (STM).

What happens when two isolated atoms are brought into very close proximity?

When two isolated atoms are brought into very close proximity, the electrons in the orbits of the two atoms interact with each other. This causes the energies of the electrons to change, with some energies becoming slightly lower and others becoming slightly higher than the original discrete energy levels.

What is the result when 'N' number of atoms are brought together to form a solid, and their electrons interact?

When 'N' number of atoms are brought together to form a solid, and their electrons interact, it results in 'N' number of closely spaced energy levels in the place of the original discrete energy levels. These closely spaced energy levels are known as bands of allowed energies. Signup and view all the answers

What are the regions between the bands of allowed energies called?

The regions between the bands of allowed energies are called the forbidden band of energies. Signup and view all the answers

What happens to the energy levels of the valence electrons in sodium (Na) metal when isolated sodium atoms are brought together to form a solid?

When isolated sodium atoms are brought together to form a solid, the energy levels of the valence electrons (3S and 3P orbitals) spread into bands. Signup and view all the answers

Why can't electrons exist in forbidden energy states?

Because there are no solutions to Schrödinger’s equation there. Signup and view all the answers

What happens when an electron experiences Bragg scattering off the lattice?

The electron goes in the opposite direction, exhibiting negative mass. Signup and view all the answers

How do electrons sometimes interact with the lattice?

Sometimes the lattice holds the free electrons in place. Signup and view all the answers

What is the significance of the band structure in crystals?

The band structure shows a gap that extends in all directions through the crystal. Signup and view all the answers

How is the energy of an electron in an atom quantized?

The electron can only take specific energy levels, no other energy levels. Signup and view all the answers

Who suggested that electrons move like standing waves on a string?

Louis de Broglie. Signup and view all the answers

What type of bonds are present in metals that allow for the free movement of electrons?

Ionic bonds Signup and view all the answers

How do electrons move in a conductor under the influence of an electric field?

In one direction Signup and view all the answers

What is the term used to describe the net momentum of electrons in a metal?

Electrical current Signup and view all the answers

What is the main difference between crystalline and amorphous solids in terms of their atomic arrangements?

Crystalline solids exhibit long-range order, while amorphous solids exhibit only short-range order in their atomic arrangements. Signup and view all the answers

What is a characteristic of bonds in crystalline solids?

Bonds in crystalline solids are more or less the same in energy. Signup and view all the answers

What is a property of amorphous solids in terms of their bonds and melting temperature?

Their bonds vary in energy and are weaker; they have no distinct melting temperature. Signup and view all the answers

Why does the 3s band broaden as the separation between sodium atoms decreases?

The 3s band broadens because as the separation decreases, the 3s atomic orbitals start to overlap and form a band. Signup and view all the answers

At what approximate interatomic separation does the 3s energy level start to increase, and why?

At about 0.36 nm, the 3s energy levels start to go up due to the particle-in-a-box effect. Signup and view all the answers

Why are the 3p and 4s bands shown in the figure, even though there are no electrons available to occupy them?

The 3p and 4s bands are shown because the bands exist in the solid, whether or not there are electrons to occupy them. Signup and view all the answers

What happens to the 1s and 2s energy levels of sodium atoms as the interatomic separation decreases?

The 1s and 2s energy levels remain as atomic states and do not form bands because the sodium atoms do not get close enough for significant overlap of these inner orbitals. Signup and view all the answers

How does the representation of energy bands shown in the figure differ from the actual band structure in a real crystal?

The representation shown is highly schematic. Real bands are not boxes or lines, and the energy levels vary with different directions in space within the crystal. Signup and view all the answers

Why does the 3s energy band of sodium contain twice as many states as there are electrons?

The 3s energy band of sodium contains twice as many states as there are electrons because sodium has a single 3s electron, and each orbital can be occupied by two electrons with opposite spins. Signup and view all the answers

What is the significance of the term 'zero net group velocity' in the context of Brillouin zone bands?

Zero net group velocity indicates the presence of flat bands, where the free electron parabola is distorted at the Brillouin zone boundaries. Signup and view all the answers

What is the Kronig-Penney model and what does it represent?

The Kronig-Penney model is a mathematical model that describes the energy levels of an electron in a periodic potential, such as that experienced by an electron in a crystal lattice. Signup and view all the answers

Explain the significance of the energy levels above the Fermi level in metals.

Above the Fermi level, the energy levels are unoccupied (empty at absolute zero) and can accept excited electrons. Signup and view all the answers

How does the absorption and re-emission of light contribute to the metallic luster of metals?

When light is incident on a metal surface, electrons can absorb the energy and jump to higher unoccupied energy levels. This creates a current that rapidly discharges, emitting a photon of the same wavelength as the absorbed light. Signup and view all the answers

Why do most metals appear white or silver in color, and why are smooth metal surfaces highly reflective?

Most metals appear white or silver because they do not allow light to penetrate deeply into the material, resulting in immediate re-emission of the absorbed light at the surface. Smooth metal surfaces are highly reflective for the same reason - they do not allow light to penetrate deeply. Signup and view all the answers

Study Notes

Atomic Structure and Solid State Physics

The universe is composed of atoms and the void, according to Edward Robert Harrison.
Gerd Binnig and Heinrich Rohrer won the Nobel Prize in 1986 for inventing the Scanning Tunneling Microscope (STM).

Band Theory in Solids

An isolated atom possesses discrete energy levels of different electrons.
When two or more atoms are brought together, their electrons interact, resulting in closely spaced energy levels.
In a solid, these energy levels form bands of allowed energies, with empty energy regions (forbidden bands) between them.
Electrons cannot exist in forbidden energy states due to Schrödinger's equation.

Energy Bands in Solids

The formation of energy bands is explained using sodium (Na) metal as an example.
The 3S and 3P orbitals electrons' energies spread into bands when isolated sodium atoms are brought together to form a solid.
Electrons can have an effective mass (m_effective) that is different from their actual mass (m_electron), sometimes even negative.
The band structure shows a gap that extends in all directions through the crystal.

Electron Behavior in Solids

The electron can take specific energy levels, with no other energy levels available.
Electrons in conductors move randomly under no influence, but under the influence of an electric field, they move in one direction.
The net momentum of electrons in metal is called electrical current.

Crystalline and Amorphous Solids

Solids are divided into two categories: crystalline and amorphous.
Crystalline solids exhibit long-range order in their atomic arrangements, with distinct melting temperature and similar energy bonds.
Amorphous solids exhibit short-range order, with varying energy bonds and no distinct melting temperature.

Electron Energy in Solids

The 3s band broadens as the interatomic separation decreases, eventually forming a band.
The 3s electron energy decreases as the separation decreases below 1 nm, then increases as the separation further decreases.
The 2p levels start to form a band at around 0.36 nm.

Band Structure and Visualization

Energy bands can be visualized using a highly schematic representation, with real bands not being boxes or lines.
The band structure varies with different directions in space.

Kronig-Penney Model

The Kronig-Penney model is used to plot energy versus wavenumber.
The model shows the relationship between energy and wavenumber for a given potential.

Metal Properties

Above the Fermi level, energy levels are empty and can accept excited electrons.
The surface of a metal can absorb all wavelengths of incident light, creating current that rapidly discharges to emit a photon of light.
This is why most metals are reflective and appear white or silver.

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Description

Test your knowledge on basic concepts in solid state physics, such as the structure of iron atom on copper, Band Theory in Solids, and the behavior of electrons in isolated atoms. Explore fundamental principles in the field of solid state physics with this quiz.