Graphite is a kind of allotrope of element carbon. The periphery of each carbon atom is connected with another three carbon atoms (arranged in honeycomb like hexagon) to form covalent molecules by covalent bond. Since each carbon atom emits an electron, which can move freely, graphite is a conductor Graphite is one of the softest minerals. Its uses include pencil lead and lubricant. Carbon is a kind of nonmetallic element, which is located in the IVA family of the second period of the periodic table.
The Latin word is carbonium, which means “coal, charcoal”. The Chinese character “charcoal” is composed of the charcoal character “charcoal” and the stone character, from the sound of “charcoal” The structural formula of high-purity graphite is formed by SP2 hybrid orbit, that is, one 2S electron and two 2p electrons hybridize to form an equivalent hybrid orbit, which is located in the same plane, with an intersection angle of 120 °, and they combine with each other to form a bond, while one 2p electron that does not participate in the hybridization is perpendicular to the plane, forming a π bond, thus forming a hexagonal parallel mesh structure of high-purity graphite, which is stacked in the direction parallel to the base plane In the parallel network layer of high-purity graphite, σ bond overlaps π bond, while in the hexagonal plane network layer, weak van der Waals molecular bond is used.
There are two kinds of stacking forms of graphite: one is hexagonal graphite, which is orderly arranged in three-dimensional space of AB and ab. the bond length between carbon atoms is – 10th Power M of 1.4211 * 10, the layer spacing d = 3.3538 * 10 – 10th Power M, and the cell side length. A = 2.4612 * 10 to the – 10th Power M, cell height C = 6.7079 * 10 to the – 10th Power M; the other is an ordered arrangement of ABC ABC in three-dimensional space, known as orthorhombic graphite, which is actually the metamorphosis of the listed hexagonal crystal system due to crystal defects. This kind of graphite accounts for 20% ~ 30% in natural graphite. When treated at 3000 ℃, it will become hexagonal system, so it does not exist in artificial high-purity graphite There is no large single crystal of graphite with ideal crystal structure of high purity graphite. Even the single crystal selected from natural flake graphite is only a few millimeters in size. However, as a scientific model, it has important guiding significance for carbon materials.
