In this video i introduce the band theory of solids by beginning with the electron energy levels in isolated atoms and then bringing them together to form a solid. A very poor conductor of electricity is termed as insulator. A solid contains an enormous number of atoms packed. When two similar atoms are brought closer, then there is an interaction between the valence electrons of these two. We know that in an atom, the protons and the neutrons constitute the central part called the nucleus. Crucial to the conduction process is whether or not there are electrons in the conduction band. The glass, wood, mica, diamond are the examples of an insulator. Calculate the absorption edge, carrier density, and electrical conductivity of a material, and predict how incident photons of given energies or wavelengths will interact with a material.
In a substance, as many atoms are close to each other, the energy levels of the atom form a continuous band, where in the electrons move. Kinetic molecular theory animation for an introduction to chemistry by mark bishop. Instead of having discrete energies as in the case of free atoms, the available energy states form bands. Next we discuss in detail periodic arrays of magnetic traps, i. Band theory of solids a useful way to visualize the difference between conductors, insulators and semiconductors is to plot the available energies for electrons in the materials. Band theory of solids energy band theory is used to study the behaviour of solids as conductors metals, insulators and semiconductors. A metal which is very good carrier of electricity is called conductor. Elementary theory for obtaining the energy levels in a band. The energy band structure of a solid determines whether it is a conductor, an insulator or a semiconductor.
Discuss in detail about the band theory of solid in detail. Pdf in isolated atoms, the electrons are orbiting around their nuclei with certain energy levels. Energy band theory in solids in a single isolated atom, the electrons in each orbit have definite energy associated with it. A quantummechanical theory of the motion of electrons in solids which predicts certain restricted ranges, or bands, for the electron energies. Ravindran, phy075 condensed matter physics, spring 20. A quantummechanical theory of the motion of electrons in solids. Detailed analysis of bond overlap populations bop found that the mmg. Band theory provides a good explanation of metallic luster and metallic colors. In insulators the electrons in the valence band are separated by a large gap from the conduction band, in conductors like metals the valence band overlaps the. Cbse ncert notes class 12 physics semiconductor electronics. A solid contains an enormous number of atoms packed closely tog ether. It is the width of these bands and their proximity to existing electrons that determines how mobile those electrons will be when exposed to an electric field. The electronic structure and chemistry of solids by p.
Band theory of solids article about band theory of. Its name comes from the fact that it predicts certain restricted ranges, or bands, for the energies of. Vbsmrc band theory 11 1d solid simple arguments since the state of the electron for k n. Each atom, when isolated, has a discrete set of electron energy levels 1s,2s,2p, if we imagine all the n atoms. Derive the band structure of a solid, starting from the orbital diagrams of individual atoms. Electrons of each isolated atom have discrete energy levels. Band theory of solids accessscience from mcgrawhill. A metal having conductivity which is between conductor and an insulator is called semiconductor. Band theory of solids the energy band structure of a solid determines whether it is a conductor, an insulator or a semiconductor. When n becomes very large, as in the case of a solid, there will be a large number of. Energy band theory in solids physics and radioelectronics.