The energy band Theory of diamond Metal Bond

Metal Bond's theory of energy band is to use the viewpoint of quantum mechanics to illustrate the formation of metal bond.

Thus, the band theory, also known as Metal Bond's quantum mechanics model, has 5 basic points of view:

1. In order to make the metal atoms of a small number of valence electrons (1, 2 or 3) can adapt to the need for high coordination, the bonding current price electrons must be "off-domain" (that is, no longer subordinate to any particular atom), all valence electrons should belong to the entire metal lattice of the atom common.

2. The metal lattice atoms are very dense, can form many molecular orbits, and the adjacent molecular orbital energy difference is very small, it can be considered that the energy changes between the various energy levels are basically continuous. 3. The energy band formed by the molecular orbit can also be regarded as the overlap of the electron energy level of the tightly stacked metal atoms, which belongs to the whole metal crystal. For example, the 1S energy levels of lithium atoms in lithium metal overlap with each other to form 1S energy bands in metal lattices, and so on.

Each band can include many similar energy levels, so each band will include a considerable range of energies, sometimes up to 418 kj/mol. 4, according to the atomic orbital energy level, metal crystals can have different energy bands (such as the above lithium metal in the 1s energy band and 2s energy band), by the electronic orbital energy level of the formation of the low power band, called "Full Band", by the non-filled atomic orbital energy levels formed by the high energy band, called "Guide belt." The energy difference between the two types of bands is so great that the electrons in the low-energy band are almost impossible to jump to the high-energy band, so the energy interval between the two energy levels is called the "Forbidden Band". For example, the 1s orbit of lithium metal (the electronic layer structure is 1S22S1) is full of electrons, the 2s orbit is not full of electrons, the 1s band is a full band, the 2s band is a guide band, the energy difference between the two is very different, the interval between them is a forbidden band, It is electrically impenetrable (that is, electrons cannot be moved from 1s to 2s band).

However, the electrons in the 2S band can move freely in the adjacent energy levels in the band while receiving external energies. 5, metal adjacent to the band can also overlap with each other, such as beryllium (electronic layer structure for 1S22S2) 2s orbit has been filled with electrons, 2s band should be a full band, it seems that beryllium should be a non-conductor.

However, because the 2s band of beryllium and the empty 2p can be very close to the energy and can overlap, the electrons in the 2s band can be upgraded into the 2p band movement, so beryllium is still a good conductive metal, and has a metal conductivity.

Conductivity The energy difference between the metal energy bands and the condition of the electron filling in the energy band determine whether the substance is a conductor, a non-conductor or a semiconductor (i.e. metal, nonmetallic or quasi-metal). If all the energy bands of a substance are full and there is a large space interval between the bands, the substance will be a non-conductor, and if the energy band of a substance is partially filled with electrons, or has a free band with a small space, it can overlap with the adjacent (electrically) band, which is a conductor. Semiconductor energy band structure is full of electrons filled, the guide is empty, and the width of the forbidden band is very narrow, in general, because the full band of electrons can not enter the guide band, so the crystal does not conduct electricity (especially at low temperatures). Because the anti-bandwidth degree is very narrow, under certain conditions, so that the full band of electrons can easily jump to the guide, so that the original empty guide belt also filled some of the electrons, while also leaving space on the full band (often called holes), so that the guide belt and the original full band are not full of electrons, so can conduct electricity.