分子间作用力（Intermolecular force）Intermolecular forceHelp edit an encyclopediaIntermolecular forceThe intermolecular force, also known as the Fan Dehua force, is, in essence, an electrical attraction, so the origin of the intermolecular force is investigated by studying the electrical and molecular structures of the molecules of matter.See the wonderful AtlasCatalogClassification of intermolecular forcesDistance philosophy from Fan Dehua's forceRelationship with hydrogen bondsFactors affecting intermolecular forceSize and physical propertiesOpenClassification of intermolecular forcesDistance philosophy from Fan Dehua's forceRelationship with hydrogen bondsFactors affecting intermolecular forceSize and physical propertiesOpenEdit this paragraphClassification of intermolecular forcesIntermolecular force refers to the force acting between molecules and molecules or functional groups of molecules within polymers, referred to as intermolecular forces. It mainly consists of:Fan Dehua force: originally proposed in order to correct the Fan Dehua equation. Ubiquitous in solids, liquids, gases, any particles, and inversely proportional to the distance between the six. According to different sources can be divided into: the dispersion force (en:London dispersion force): the electrical attraction between the instantaneous dipole orientation; force (dipole-dipole force): electric dipole attraction between the electrically induced force; induced dipole and dipole attraction between hydrogen bonds: X-H... Y type of force. In addition, novel intermolecular forces have also been reported, including double hydrogen bonds and gold bonds.Definition: Fan Dehua force (also called molecular force) arises from electrostatic interaction between molecules or atoms. The empirical equation for calculation of energy: U =B/r 12- A/r (6 to 2 carbon atoms, the parameter values for B =11.5 * 10-6 kJnm^12/mol * 10-3; A=5.96 kJnm^6/mol; A B, different atoms have different values) when the two atoms are close to each other near the electronic cloud overlap, has strong rejection, rejection force and distance is inversely proportional to the square of 12 times. The low point in the figure is the distance Fan Dehua forces maintain and the maximum force is called the Fan Dehua radius.Vander Ed Ley can be divided into three kinds of forces: induction force, dispersion force and orientation force.Dispersion forceAtomic interior model of particlesDispersion force, also known as the force of London, all molecules or atoms exist. Is the force between the instantaneous dipole, that is due to the movement of electrons, the instant electronic position is the asymmetry of atomic nuclei, i.e. positive charge center and negative charge center instantaneous do not overlap, resulting in instantaneous dipole. The dispersion force and the deformation of the interacting molecules are related. The larger the deformation (the greater the general molecular weight, the greater the deformability), the greater the dispersion force. The dispersion force is related to the ionization potential of the interacting molecules. The lower the ionization potential ofthe molecule (the more electrons there are in the molecule), the greater the dispersion force. The interaction of the dispersion force varies with 1/r6. Its formula is:I1 and I2 are the ionization energies of two interacting molecules, respectively. Alpha 1 and alpha 2 are their polarizability.Inductive forceInductive force (induction, force) has an inductive force between polar molecules and nonpolar molecules, and between polar molecules and polar molecules. Due to the polar molecular dipole generated by the electric field on the non-polar molecules, the nonpolar molecule electron cloud deformation (i.e. the electron cloud is attracted to the polar molecular dipole positive pole), the non polar molecules and electron cloud nuclei occur relative displacement, have non positive and negative focus in charge of polar molecules is coincidence, the relative displacement will no longer coincide, the non-polar molecules produced a dipole. The relative displacement of the charge center is called deformation. The dipole produced by deformation is called the induced dipole, which is distinguished from the intrinsic dipole in the polar molecule. The induced dipole and the intrinsic dipole attract each other, and the force induced by the dipole is called the induced force. In polar molecules and polar molecules, in addition to the orientational force, each molecule deforms and induces an induced dipole due to the interaction of polar molecules. As a result, the dipole distance increases with both the orientational force and the induced force. An induced force isalso found between cations and anions.The induced force is proportional to the square of the dipole moment of the polar molecule. The induced force is proportional to the deformation of the induced molecule. The larger the outer shell of the nucleus in each molecule (the more heavy atoms), the more easily it becomes deformed under the influence of external electrostatic force. The interaction changes with 1/r6, and the induction force is independent of temperature. Its formula:Alpha polarizability.Orientation forceThe orientational force (orientation, force) of the orientational force occurs between the polar molecule and the polar molecule. Because of the uneven distribution of the molecules of the polar molecule, one end is positively charged and one end is negatively charged, forming a dipole. Thus, when the two polar molecules are close to each other,Because of their dipole poles repel, heteropolar, relative rotation of two molecules will occur. The dipole rotates so that the opposing poles of the dipole are called "orientations"". Because the opposite pole is close, very far, the gravity is bigger than the repulsion, two molecules near, when close to a certain distance, attraction and repulsion balance. The intermolecular forces produced by the orientation of polar molecules are called orientational forces. The orientational force is proportional to the square of the dipole moment of themolecule, i.e., the greater the polarity of the molecule, the greater the orientation force. The orientation force is inversely proportional to the absolute temperature. The higher the temperature, the weaker the orientation force and the change of the interaction with the 1/r6. Its formula is:1, mu 2 is the dipole moment of two molecules; R is the distance between the molecular center of mass; K is Boltzmann constant; T is thermodynamic temperature; negative value means energy decrease.The relation of three forcesBetween polar molecules and polar molecules, orientation force, induced force, dispersion force exists; between polar and non-polar molecule, is induced and dispersive; between non polar and non-polar molecules, then there is only the dispersion force. The size of these three types of forces depends on the polarity and deformability of the interacting molecules. The greater the polarity, the more important the orientation force; the greater the deformation, the more important the dispersion force; the induction force is related to these two factors. But for most molecules, dispersion is the main force. Experiments have shown that for most molecules, the dispersion force is the main; only the dipole moment of large molecules (such as water), the orientation force is the main; and the induction force is usually very small. The polarizability alpha reflects whether the electron cloud in the molecule is susceptible to deformation. Although van Edward's force is only 0.4 - 4.0kJ/mol, the interaction between a large number of macromolecules can be very stable. For example, C -H in benzene, van Edward force has 7 kJ/mol, and in lysozyme and sugar bound substrate van, Edward force has 60kJ/mol, van Edward force has additivity.The molecular forces, ionic bonds, salt bonds, and covalent bonds are all electrostatic attraction. Why is the gap so great?So the real keyword is "distance", and we can consider the molecular force and the ionic bond together.Types of action energy and distance relationsElectrostatic interaction of charged groups 1/rIon dipole 1/r2Ion induced dipole 1/r4Dipole dipole 1/r6 alignment force chemistryDipole induced dipole 1/r6 induced forceInduced dipole induced dipole 1/r6 dispersion forceNon - bond exclusive 1/r12 - 1/r6In secondary school, we studied ionic bonds, and the crystal configuration of six typical compounds, NaCl, CsCl, CaF2, cubic ZnS, six party ZnS and rutile TiO2, is a strong force.In biology, the focus is on understanding the ionicinteractions of organic molecules. Ion organic molecules, electronegativity difference is not so large, unlike the interaction of these typical ionic compounds such as ionic bond, so called ion interaction; but they have in common are electrostatically formation.NaCl, CsCl, CaF2 crystal, cubic ZnS, six party ZnS, rutile TiO2 six typical compounds of the ionic bond is an energy and distance is inversely proportional to the square, the interaction between Mg2+ and ATP, the interaction between the zwitterionic amino acids. The ion dipole decreases with the two side of the distance, and the ion induced dipole decreases with the 4 side of the distance. Therefore, the interaction of ions in biological molecules (also called salt bonds) is a weak interaction, and decreases with the 1/r2 - 1/r4.Interaction of ATP with magnesium ionThe van Edward force includes gravity and repulsion, gravity and distance of the 6 side is inversely proportional to the repulsion force and the 12 side of the distance is inversely proportional. They are static electricity, springing up at different levels.Edit this paragraphDistance philosophy from Fan Dehua's forceVan Edward's force is well understood, which is different from the quark's progressive freedom. In Confucius's words, "near is rude, far away."." Between people need to have a certaindistance between the mind, far away will be lonely, need to draw close to each other; near, the contradiction will intensify. For the atom, this paradox is inversely proportional to the 12, and the attraction is inversely proportional to the 6. The distance between atoms can be approximately measured, but the distance between man and mind is not measurable......There is also a safe distance between people. Duncan, a master of American psychology, said: "1.2 meters is the safe distance between people.". Unless it's someone you trust, know or get close to, it's going to make you feel insecure, whether it's talking or other communication. On the street to and fro stream of people, two people, a group, three people, a group of, before and after the distance between each other are mostly kept within a certain distance,It's also a subconscious security precaution; there's one meter safety line in front of the atm. Take care of yourself and you'll find the safe distance is with usEdges are visible everywhere. Some people say that marriage is a siege, the people who do not go in want to go in; people who go in and want to come out. The distance between people is often greater than the life of the "Fan Dehua radius", less trust each other.After entering the marriage besieged city, they longed for each other's heart distance to be closer, became no longer lonely, also was precisely because crossed the humanSelf boundaries will have suspicion, mistrust,misunderstanding, longing for each other to pay more, worry about personal gains and losses, more demanding to each other, and ultimately like quarks and fermions as to the "asymptotic freedom" to constitute a society now divorce. If people are too far away from each other, people will be lonely, unable to rely on, will become no longer trust others, and then be excluded from society. Everyone has to find the inner integrity and keep the right distance from different people. This is the "Fan Dehua radius" of life, which is the philosophy of molecules, and also the philosophy of man.Edit this paragraphRelationship with hydrogen bondsThe essence of hydrogen bonding is the electrostatic attraction between a hydrogen nucleus with a strong polar bond (A-H) and an electronegative electric atom containing an unpaired electron pair and an atom with partial negative charge B. Hydrogen atoms can be combined with 2 electrically electronegative atoms with small atomic radii (such as O, N, F, etc.). In X - H... Y, X, and Y are atoms with large electronegativity, small atomic radii, and electrons with no shared electrons. X H, X has a strong electronegativity, the electron density of X - H bond bias in the X end, and H shows a partial positive charge; another molecule in Y but also a concentration of the electron cloud and significantly negative, it and H with static electricity combined, this is the nature of hydrogen bonds. Therefore, the electrostatic attraction of hydrogen bonds is usually called the Fan Dehua force, and the difference is that it is saturated and directional. This forceis generally below 40kJ/mol, much smaller than the average bond energy.From the point of view of physics and mechanics, it can be divided into gravitation and repulsionGravitation:When an external force tries to stretch an object, a large number of molecules that make up the object will show gravity to resist the pull of the outside.Although there are gaps between molecules, a large number of molecules can cluster together to form solid and liquid, indicating the existence of gravitational attraction between molecules.Solids hold a definite shape to indicate gravitational attraction between molecules.Repulsion：When an external force tries to compress an object, a large number of molecules forming an object will exhibit repulsion to resist the compression of the outside.There are gravitational forces between molecules, but molecules do not stick together, but there are gaps, indicating that there is repulsion between molecules.Edit this paragraphFactors affecting intermolecular forceHydrogen bond, polarity of bond and relative molecular weight. The radius (similar to the ion compound), the greater the radius, the farther the distance, the weaker the ionic bond, the lower the boiling pointEdit this paragraphSize and physical propertiesMaterial composition and structure similarity, the higher relative molecular mass and the Fan Dehua stress is, to overcome the intermolecular force of the material melting and vaporization on the need for more energy, the higher the melting and boiling points. But there are hydrogen bonds of boiling point and melting point of molecular crystals are abnormally high. The distance between gas molecules is large, so the small molecular interactions; liquid and solid, it is proved that intermolecular attraction effect; and the liquid and solid to compression, and that rejection showed in near distance between molecules.The solid is difficult to stretch, intermolecular force performance, so the A of B; the liquidity is not in liquid illustrated with gravitation and repulsion, its reason is the chemical bond effect; C, the gas molecules even without compression or repulsion, but smaller, D that the steel intermolecular voids, the oil overflows from the tube, is the result of external factors, but not on steel. The molecularrepulsion of oil molecules to [1]。
