What is the Difference Between Energy Level and Energy Band?

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The difference between energy levels and energy bands lies in their quantum nature and the way they are affected by the presence of other atoms or molecules:

  • Energy Levels: These are quantized energy values of an atom, representing specific and discrete energy states for electrons. In an isolated atom, electrons in each orbit have a definite amount of energy. However, when two isolated charges are brought close together, the electrons in the outermost orbit experience an attractive force from the neighboring atomic charges, causing their energy levels to change.
  • Energy Bands: These are continuous combinations of energy levels of electrons in a molecule or solid. In a solid, the energy levels of electrons are influenced by the neighboring atoms, causing the energy levels of the electrons in the same orbit to exhibit a range of different energy levels. Energy bands are formed due to the overlapping of atomic orbitals in solids, which leads to a continuous distribution of energy levels.

The key difference between energy levels and energy bands is that energy levels exist at the atomic level, while energy bands are a result of the interaction between electrons and the surrounding atoms or molecules. Energy levels are discrete values, whereas energy bands are continuous combinations of energy levels.

Comparative Table: Energy Level vs Energy Band

The key difference between energy levels and energy bands is that energy levels are quantized energy values of an atom, while energy bands are continuous combinations of energy levels of electrons in a molecule. Here is a table summarizing the differences between energy levels and energy bands:

Energy Levels Energy Bands
Discrete, quantized energy values of an atom Continuous combinations of energy levels of electrons in a molecule
Exist at the atomic level Exist at the molecular level
Energy levels are forbidden energies that cannot be occupied by electrons Energy bands are formed when energy levels of atoms are modified due to the influence of nearby atoms in a solid
The energy band gap is the difference in energy between the top of the valence band and the bottom of the conduction band in a solid The energy band gap is the energy range that cannot be occupied by electrons due to the influence of nearby atoms

In summary, energy levels are discrete values of energy for individual atoms, while energy bands are continuous combinations of energy levels that arise in molecules or solids due to the influence of neighboring atoms. Energy bands can have a band gap, which is the energy difference between the top of the valence band and the bottom of the conduction band. This band gap represents an energy range that cannot be occupied by electrons.