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Difference Between Conduction Band and Valence Band for JEE Main 2024

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Last updated date: 14th Jul 2024
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What is Conduction Band and Valence Band:Introduction

The conduction band and valence band, known as the bands in solid-state  that are closest to the Fermi level, control the solid's electrical conductivity. The conduction band is the lowest range of unoccupied electronic states in nonmetals, while the valence band is the highest range of electron energies where electrons are typically present at absolute zero temperature. The valence band is below the Fermi level on a graph of a material's electronic band structure, and the conduction band is above it.


Category:

JEE Main Difference Between

Content-Type:

Text, Images, Videos and PDF

Exam:

JEE Main

Topic Name:

Difference Between Conduction Band and Valence Band

Academic Session:

2024

Medium:

English Medium

Subject:

Chemistry

Available Material:

Chapter-wise Difference Between Topics


Conduction Band:

When charged, electrons can move from the valence band into the band of electron orbitals known as the conduction band. The electrons have sufficient energy to move freely within the material when they are in these orbitals. Electric current flows as a result of the movement of electrons. The farthest electron orbital of an electron-containing particle in a specific material is called the valence band.


The bandgap, which indicates the electrical conductivity of a material, is the energy difference between the least abandoned condition of the conduction band and the lowest occupied energy state of the valence band. A large bandgap indicates that valence electrons must be energized to the conduction band with a great deal of energy. However, when the valence band and conduction band overlap, as they do in metals, electrons can instantly bounce between the two groups, indicating that the substance is extremely conductive.


  • Conductor:

In the fabrication of semiconductors, contacts and interconnects are made from a material with low resistivity. In a conductor, the valence band and conduction band crossover. In a conductor, the conduction band is thus analogous to the valence band, and electrons serve as the primary charge carriers.


  • Conductivity:

In the end gap, which is a measure of a material's electrical conductivity, is the energy difference between the lowest unoccupied state of the conduction band and the lowest occupied energy state of the valence band. It takes a lot of energy to excite valence electrons to the conduction band when the band gap is large. On the other hand, electrons are formed when the valence band and conduction band overlap, as they do in metals.


Valence Band:

The outermost electron orbital that electrons actually occupy in an atom of any particular material is known as the valence band. When excited, electrons have the ability to jump out of the valence band and into the conduction band. This and the notion of the valence electron are closely related.


The overlapping atomic orbitals are located.


  1. Sigma bonds and pi bonds are formed differently depending on how the atomic orbitals overlap; pi bonds are created by side-to-side overlapping, whereas sigma bonds are created by overlapping along the axis that contains the nuclei of the two atoms.


  • Valence Bond Theory principles :

The following is a list of the key valence bond theory postulates.


When two valence orbitals (half-filled) from two different atoms cross over one another, covalent bonds are created. This overlapping increases the electron density in the region between the two bonding atoms, increasing the stability of the resulting molecule.


An atom's valence shell, which contains a large number of unpaired electrons, allows it to form a variety of bonds with other atoms. According to the valence bond theory, the paired electrons in the valence shell do not contribute to the synthesis of chemical bonds.


Covalent chemical bonds have a direction and run parallel to the area where hapter on current electricity, we already defined resistivity. Conductivity, which is the opposite of resistivity, is relevant in this situation. The ability of a material to conduct electrons is determined by its conductivity. Because copper has a conductivity of $5.95 \times 10^7$ W-1m-1, more electricity can move through it than through aluminum. In comparison to copper, aluminum has a slightly lower conductivity, $3.77 \times 10^7$ W-1m-1. 


Differentiate Between Conduction Band and Valence Band :

S No.

Conduction Band

Valence Band 

1

Band with a higher energy level

Numerous energy levels with valence electrons come together to form an energy band.

2

Filled just partially by the electrons

Constantly containing electrons

3

Energy state is high.

Energy state is low.

4

Above the Fermi level

Below the Fermi level

5

When an atom is excited, electrons transition into the conduction band.

When the atom is excited, electrons will leave the conduction band.

6

Current flows due to these electrons.

The highest energy level that an electron in the valence band can occupy at 0 K.


Conclusion:

The two different energy levels of the valence and conduction bands are spaced apart by a predetermined amount of energy. The valence band distinguishes the energy level of the electrons present in the valence shell of an atomic structure, whereas the conduction band does not. In contrast, a conduction band contains the electrons necessary for conduction. The term "forbidden energy gap" refers to the energy difference between the valance band and the conduction band.


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FAQs on Difference Between Conduction Band and Valence Band for JEE Main 2024

1. What are the applications of valence band theory?

Applications of valence band theory:


  • The formation of covalent bonds in multiple molecules can be explained by the maximum overlap condition, which is outlined by the valence bond theory.

  • One of its most crucial applications is this. For instance, the different overlapping orbitals in H2 and F2 molecules can be used to explain the variation in the length and strength of the chemical bonds in these molecules.

  • According to the valence bond theory, the covalent bond in an HF molecule is created by the overlap of the hydrogen atom's 1s orbital and the fluorine atom's 2p orbital.

2. What are the limitations of valence band theory?

The limitations of valence band theory


  • Limitations of valence band theory:

  • Failure to provide an explanation for carbon's tetravalency.

  • On the energies of the electrons, nothing is said.

  • The theory presupposes that electrons are regionally localized.

  • The thermodynamic or kinetic stabilities of coordination compounds are not quantitatively explained.

  • There is no distinction between strong and weak ligands.

  • There is no explanation for the color coordination compounds display.

3. Describe the band structure of sodium.

  • Forbidden gaps - The forbidden gap is the space or energy difference between the valence band and the conduction band. 

  • Conductors - Materials that permit the flow of electricity through them are referred to as conductors. Copper, iron, zinc, and other examples. 

  • Semiconductors - The term "semiconductors" refers to materials that exhibit conductivity between conductors and insulators. Examples include Si, Ge, and As. 

  • Insulators - Materials that prevent electricity from passing through them are referred to as insulators. Examples include wood, glass, and stones. You are now prepared to understand band theory after understanding all of these terms. 

4. Define fermi level.

The energy level that the electron orbital occupies at absolute zero degrees Celsius is known as the Fermi Level. The conductivity of various materials is dependent on occupancy levels. An approximate calculation based on the crystalline structure can be used to determine the orbital occupancy for solid materials like metals. The energy level and these orbitals work together to determine whether a substance is an insulator, semiconductor, or conductor. The energy of the orbitals determines how they are grouped. The higher energy orbitals combine to form the conduction band, while the lower energy orbitals combine to form the valence electron band. The energy gap, which separates the valence and conduction bands, is the factor that determines how much energy is present.

5. What are the key difference between conduction band and valence band ?

Key differences between conduction band and valence band :


  • Below the fermi energy level, the valence band is present. While the conduction band is visible in the energy band diagram above the Fermi level.

  • Comparatively speaking, the valence band has a higher electron density than the conduction band.

  • The valence band is typically either fully or partially filled at room temperature. At room temperature, the conduction band is typically empty or only partially filled.

  • The conduction band is comparatively more energetic than the valence band, which is in a lower energy state.