Views: 28 Author: Site Editor Publish Time: 2022-06-22 Origin: Site
Silver white metal. It is soft and can be cut with a knife. It is the lightest metal with a density smaller than that of all oils and liquid hydrocarbons, so it should be stored in solid paraffin or white vaseline (lithium will float in Liquid Paraffin).
The density of lithium is very small, only 0.534g/cm ³， It is the smallest of non gaseous simple substances.
Because of its small atomic radius, lithium has the smallest compressibility, the largest hardness and the highest melting point compared with other alkali metals.
When the temperature is higher than -117 ℃, lithium metal is a typical body centered cubic structure, but when the temperature drops to -201 ℃, it begins to transform into face centered cubic structure. The lower the temperature, the greater the degree of transformation, but the transformation is incomplete. At 20 ℃, the lattice constant of lithium is 3.50 μ m, and the conductivity is about one fifth of that of silver. Lithium readily fuses with any metal other than iron.
The flame reaction of lithium is purplish red.
There are seven isotopes in lithium, two of which are stable, Li-6 and Li-7. In addition to stable isotopes, li-8 has the longest half-life, with a half-life of 838 milliseconds, followed by li-9, with a half-life of 187.3 milliseconds, and other isotopes have a half-life of less than 8.6 milliseconds. LI-4 has the shortest half-life among all isotopes, only 7.58043 × 10-23 seconds.
Li-6 has a strong ability to capture low-speed neutrons, which can be used to control the speed of nuclear reactions in uranium reactors. At the same time, it can also be used in radiation protection and prolonging the service life of nuclear missiles, as well as in nuclear powered aircraft and spacecraft in the future. Li-6 can be irradiated by neutrons in nuclear reactors to obtain tritium, which can be used to realize thermonuclear reactions. Li-6 can be used as coolant in nuclear installations.
Lithium is a chemical element. It is a metal with strong metal activity (cesium is the most metallic metal). Its chemical symbol is Li. Its atomic number is 3. There are three electrons, two of which are distributed in the k layer and the other in the L layer. Lithium is the lightest of all metals. Because lithium has a large charge density and a stable helium type double electron layer, lithium is easy to polarize other molecules or ions, but it is not easy to polarize itself. This affects the stability of it and its compounds.
Although the hydrogen standard potential of lithium is the most negative, which has reached -3.045, due to the low solubility of lithium hydroxide and the exothermic reaction between lithium and water can not melt lithium, the reaction between lithium and water is not as intense as that of sodium. After a period of time, the nitrogen oxide film on the surface of lithium is dissolved, making the reaction more intense. It is easy to react with hydrogen at about 500 ℃ to produce lithium hydride. It is the only alkali metal that can generate hydrides stable enough to melt without decomposition. Its ionization energy is 5.392ev, and can combine with oxygen, nitrogen, sulfur, etc. it is the only alkali metal that reacts with nitrogen at room temperature to produce lithium nitride (Li ₃ n). Darkening due to susceptibility to oxidation. If lithium is thrown into concentrated sulfuric acid, it will float quickly on the sulfuric acid, burn and explode. If lithium and potassium chlorate are mixed (shaken or ground), it may also react explosively.
Lithium hydride reacts violently with water to produce a large amount of hydrogen. After the decomposition of two kilograms of lithium hydride, 5.66 kiloliters of hydrogen can be released. Lithium hydride is indeed a well deserved "factory for producing hydrogen". During the Second World War, American pilots had a portable hydrogen source, lithium hydride pills, for emergency use. When the plane crashed and fell on the water, as soon as it touched the water, lithium hydride immediately reacted with the water, releasing a large amount of hydrogen to inflate the life-saving equipment (lifeboat, life jacket, signal balloon, etc.).