Ions are charged particles formed by the loss or gain of one or more electrons by atoms or atomic groups. This process is called ionization. The energy required or released by the ionization process is called ionization energy.
Ions are charged particles formed by atoms or atomic groups losing or gaining one or more electrons. This process is called ionization. The energy required or released in the ionization process is called ionization energy.
In the chemical reaction, the metal element atom loses the outermost layer electron, the nonmetal atom obtains the electron, thus causes the atom or the atomic group which participates in the reaction to carry the electric charge. Charged atoms are called ions, positively charged atoms are called cations, and negatively charged atoms are called anions. Anions and cations are charged free compounds due to electrostatic action.
Like molecules and atoms, ions are also the basic particles of matter. For example, sodium chloride is composed of chloride ions and sodium ions.
Ions are charged particles formed by the loss or gain of one or more electrons by atoms or atomic groups.
When an atom gets one or more electrons, the number of protons
When an atom loses one or more electrons, the number of protons is greater than the number of extranuclear electrons, and the number of protons = the number of extranuclear electrons + the number of charges carried, thus carrying a positive charge.
Complex ions are complex ions formed by some molecules, atoms or cations through coordination bonds with electrically neutral molecules or anions, such as hydrated ions. The complex ions themselves can be cations or anions.
在化合物的原子间进行电子转移而生成离子的过程称为电离，电离过程所需或放出的能量称为电离能。电离能越大，意味着原子越难失去电子。 离子化合物，即阴、阳离子间以离子键组成的化合物，如可溶于水的酸、碱、盐，当在水中溶解并电离时，恒定条件下，处于离子状态的比例和处于分子状态的比例达到动态平衡，称为离子平衡（ion balance）。
The process of ion generation by electron transfer between atoms of a compound is called ionization, and the energy required or released in the ionization process is called ionization energy. The higher the ionization energy, the harder it is for an atom to lose electrons. Ionic compounds, that is, compounds composed of ionic bonds between anions and cations, such as water-soluble acids, bases and salts, when dissolved and ionized in water, under constant conditions, the proportion in the ionic state and the proportion in the molecular state reach dynamic equilibrium, which is called ion balance.
Like the atomic structure diagram, the ionic structure diagram can be used to represent the nuclear charge number and electronic layer arrangement of ions. The numbers in the circle and the circle indicate the number of protons in the nucleus and nucleus respectively. The arc represents the electron layer, and the number on the arc represents the number of electrons in the layer.
A brief history of discovery
1887 年，28 岁的阿仑尼乌斯在前人研究的
In 1887, at the age of 28, Arrhenius studied
Gas element ion
都有一定数量的原子被电离。在气体放电过程中以及受控聚变装置产生的高温等离子体中，有大量的工作气体原子和杂质原子被剥离了最外层电子，成为离子。例如氧原子，若失去一个电子记作 OⅡ，若失去两电子记作 OⅢ，以此类推。
A certain number of atoms are ionized. In the process of gas discharge and high temperature plasma produced by controlled fusion device, a large number of working gas atoms and impurity atoms are stripped off the outermost layer of electrons and become ions. For example, for oxygen atom, if one electron is lost, it is recorded as o Ⅱ; if two electrons are lost, it is recorded as o Ⅲ, and so on.
Ion detection refers to the process of identifying ions by indicator, precipitation, bubbling and other methods.
SO42 – (in the solution) – dilute hydrochloric acid is added to acidify first. If there is no precipitation and no gas (excluding the interference of silver ion and carbonate ion respectively), barium chloride solution is added to the measured solution to generate white precipitate, then sulfate ion is contained in the original measured solution.
CO32 – (1) (solid or solution) – dilute acid solution is added to the tested material. If the gas that can make the clarified lime water turbid is generated, the original measured material contains carbonate ion. (2) If the solution containing silver chloride is added to the solution, it can precipitate into white solution.
NH4+ （溶液或固体）———在被测物质中加入强碱如 NaOH，研磨或加热，如果放出刺激性气体，且该气体能使湿润的红色石蕊试纸变蓝，则原物质中含有铵根离子。
NH4 + (solution or solid) – add strong alkali such as NaOH to the tested substance, grind or heat it. If irritant gas is released and the gas can make the wet red litmus test paper blue, the original material contains ammonium ion.
Fe2+ （溶液）———在被测溶液中加入 KSCN 溶液，无现象，再加入新制氯水，然后，如果产生血红色沉淀，则原被测溶液中含有亚铁离子。
Fe2 + (solution) – add KSCN solution to the solution to be tested, no phenomenon, and then add new chlorine water. If blood red precipitation occurs, the original solution to be tested contains ferrous ion.
Fe3+ (溶液中）———在被测物质中加入 KSCN 溶液，如果产生血红色沉淀，则原被测溶液中含有铁离子。
Fe3 + (in solution) – if KSCN solution is added to the substance to be measured, if blood red precipitation occurs, the original solution to be measured contains iron ions.
Na + (solid or solution) – by flame reflection test, if the flame is yellow, the original material contains sodium ions.
K + (solid or solution) – Test by flame color reflection. If the flame is purple (yellow light filtered through blue cobalt glass), the original material contains potassium ion.
Non metallic ions
Dilute nitric acid solution is added to acidify the solution. If white precipitate is formed, the original solution contains chloride ion.
Br – (solution) – if silver nitrate solution is added to the tested solution, if a light yellow precipitate insoluble in nitric acid is formed, the original measured solution contains bromine ion.
I – (solution) – if silver nitrate solution is added to the tested solution, if the yellow precipitate insoluble in nitric acid is formed, the original measured solution contains iodine ion.
In the identification of sulfate ion, barium chloride solution should be used instead of silver nitrate or barium nitrate solution. This is because silver sulfate is a slightly soluble substance, so the identification phenomenon is not obvious; and nitrate is likely to oxidize sulfite to sulfate, resulting in incorrect results.
When testing sulfate ion, barium chloride solution can not be directly added. If white precipitate insoluble in nitric acid is produced, the original measured solution may contain silver ion or sulfate ion, so hydrochloric acid should be added first to acidify and eliminate silver ion.
Ion symbol: the symbol indicating the number of positive and negative charges carried by the ion in the upper right corner of the element symbol. For example, a sodium atom loses an electron and becomes a sodium ion with a unit positive charge, expressed as “Na +”. After sulfur atom obtains two electrons, it carries element symbol: the first letter of Latin name of the element is adopted to represent the symbol of the element (the number of positive and negative charges is usually written in front of the sign).
Ionic bond: electrostatic action that binds anions and cations into compounds.
离子键是由电子转移（失去电子者为阳离子，获得电子者为阴离子）形成的。即正离子和负离子之间由于静电引力所形成的化学键。离子既可以是单离子，如 Na+、Cl-；也可以由原子团形成；如 SO42-，NO3-等。离子键的作用力强，无饱和性，无方向性。离子键形成的矿物总是以离子晶体的形式存在。
The ion bond is formed by electron transfer (the electron losing is cation, and the electron gaining is anion). That is, the chemical bond formed between positive ions and negative ions due to electrostatic attraction. Ions can be either single ions, such as Na +, Cl -, or formed by atomic clusters, such as SO42 -, NO3 -, etc. The ionic bond has strong force, no saturation and no directionality. Minerals formed by ionic bonds always exist in the form of ionic crystals.
Research shows that atoms in molecules or crystals are not simply stacked together, but there is a strong interaction. Chemically, the strong force between atoms in this molecule or crystal (sometimes the gain and loss of electrons of atoms turn into ions) is called chemical bond. The essence of a bond is a force. So some are also called bond force, or bond force.
Minerals are composed of atoms, molecules or ions, which are linked by chemical bonds.
There are three basic types of chemical bonds: ionic bonds, covalent bonds and metal bonds.
Formation of covalent bond
Formation of ionic bond
1.非极性共价键形成共价键的电子云正好位于键合的两个原子正中间，如金刚石的 C—C 键。
1. The electron cloud forming the covalent bond is located in the middle of the two bonded atoms, such as the C-C bond of diamond.
2.极性共价键 形成共价键的电子云偏于对电子引力较大的一个原子，如 Pb—S 键，电子云偏于 S 一侧，可表示为 Pb→S。
2. The electron cloud of covalent bond formed by polar covalent bond is biased to an atom with strong electron attraction, such as Pb-S bond. The electron cloud leaning to s side can be expressed as Pb → s.
3.配价键 共享的电子对只有一个原子单独提供。如 Zn—S 键，共享的电子对由锌提供，Z：+ ¨．．S：=Z n→S 共价键可以形成两类晶体，即原子晶体共价键与分子晶体。原子晶体的晶格结点上排列着原子。原子之间有共价键联系着。在分子晶体的晶格结点上排列着分子（极性分子或非极性分子），在分子之间有分子间力作用着，在某些晶体中还存在着氢键。
3. The electron pairs shared by valence bonds are provided by only one atom. For example, Zn-S bond, the shared electron pair is provided by zinc, and Z: + → s: = Z n → s covalent bond can form two kinds of crystals, namely atomic crystal covalent bond and molecular crystal. Atoms are arranged on the lattice node of atomic crystal. There are covalent bonds between atoms. Molecules (polar or nonpolar) are arranged on the lattice nodes of molecular crystals. There are intermolecular forces between the molecules, and there are hydrogen bonds in some crystals.
Reaction between ions
It solidifies into liquid chlorine, ammonia and dry ice (the crystal of carbon dioxide). It shows that there is another kind of force between molecules, which is called intermolecular force (van der Waals force), and some are called molecular bonds. The intermolecular force depends on the polarity of the molecule. Molecules have polar molecules and nonpolar molecules, which are based on whether the positive and negative charge centers in the molecules coincide. Those who overlap are nonpolar molecules, and those that do not coincide are polar molecules. The intermolecular force includes three kinds of forces: dispersion force, induction force and orientation force.
(1) When nonpolar molecules are close to each other, it is impossible to make the positive and negative charge centers coincide at every moment due to the continuous motion of electrons and the continuous vibration of atomic nucleus. At a certain moment, there will always be a dipole, which is called instantaneous dipole. Because the same pole repels and the opposite pole attracts, the intermolecular force between the instantaneous dipoles is called dispersion force. When any molecules (polar or nonpolar) are close to each other, there is a dispersive force.
(2) When polar and nonpolar molecules are close to each other, in addition to the dispersive force, the induced dipole of nonpolar molecules is produced by the electric field of polar molecules. The attraction between the induced dipole and the intrinsic dipole of polar molecules is called the induced force. At the same time, the induced dipole acts on the polar molecules, which makes the dipole length increase. Thus, the attraction between them is further strengthened.
(3) When the polar molecules are close to each other, the dispersion force also plays a role. In addition, due to the mutual repulsion and attraction between the two intrinsic dipoles, the two molecules are oriented according to the state of the adjacent poles in space. The intermolecular force caused by the orientation between the intrinsic dipoles is called orientation force. Due to the existence of orientation force, the polar molecules are closer to each other. Under the action of the inherent dipole of adjacent molecules, the positive and negative charge centers of each molecule are more separated, resulting in an induced dipole. Therefore, there is still an induced force between polar molecules.
In a word, there are only dispersion forces between nonpolar molecules, dispersion forces and induced forces between polar and nonpolar molecules, dispersion forces, induced forces and orientation forces between polar molecules. The sum of dispersion force, induced force and orientation force is called intermolecular force. The intermolecular force has no directivity and saturation, and the bond force is weak.
Ions are the basic particles of ionic compounds. Ionic compounds exist in the form of ions in any state (crystal, molten state, vapor state or solution). Therefore, the properties of ions determine the properties of ionic compounds to a great extent. In other words, the properties of ions, namely the three important characteristics of ions: the charge of ions, the radius of ions, and the type of electronic layer structure of ions (referred to as the electronic configuration of ions) are the fundamental reasons that determine the commonness and characteristics of ionic compounds.
(1) The charge of an ion
离子电荷对于离子的性质以及所组成的离子型化合物的性质，都有很大影响。即使是同一种元素，当形成不同电荷的离子时，由它们所组成的离子型化合物的性质也会有较大的差异。例如，铁元素能形成 Fe2+、Fe3+两种离子，这两种离子及其化合物在性质上就大不相同。Fe3+比 Fe2+的正电荷多，在一定条件下，Fe3+能夺取 1 个电子变成 Fe2+，而相反，Fe2+则有失去 1 个电
Ionic charge has a great influence on the properties of ions and ionic compounds. Even for the same element, when ions with different charges are formed, the properties of ionic compounds composed of them will be greatly different. For example, iron can form two kinds of ions, Fe2 + and Fe3 +, which are quite different in properties. Fe3 + has more positive charge than Fe2 +. Under certain conditions, Fe3 + can capture one electron to become Fe2 +, while Fe2 + loses one electron