Beryllium is a gray alkaline earth metal, and beryllium and its compounds are very toxic. Beryllium is an amphoteric metal, which is soluble in acid and alkali solutions. Beryllium is mainly used to prepare alloys.
Beryllium is a steel gray light metal. Beryllium has higher hardness than similar metals, unlike calcium, strontium and barium, which can be cut with a knife. Beryllium has 12 isotopes, of which 4 protons and 5 neutrons are stable, so the average relative atomic mass of beryllium is 9.
Beryllium, like lithium, forms a protective oxide layer in the air, so it is stable even if it is red and hot in the air. Insoluble in cold water, slightly soluble in hot water, soluble in dilute hydrochloric acid, dilute sulfuric acid and potassium hydroxide solution to release hydrogen. Even at higher temperature, beryllium has obvious corrosion resistance to oxygen-free sodium metal. The valence of beryllium in the compound is positive 2, which can form polymers and a class of compounds with significant thermal stability.
The valence electron shell structure of beryllium atom is 2s2, the atomic radius is 89pm, the ionic radius is 3 1pm, and the electronegativity is 1.57. Beryllium has very small atomic radius and ionic radius (not only smaller than other elements in the same family, but also smaller than alkali metal elements) and relatively high electronegativity (not only higher than alkali metal elements, but also higher than other elements in the same family). Unlike other elements in the same family, beryllium has a significant tendency to form valence bonds. Therefore, beryllium often shows abnormal properties different from other elements in the same family.
Beryllium does not react with water because it is easy to form a dense protective film on its surface, while other metals of the same family, such as magnesium, calcium, strontium and barium, are easy to react with water. Beryllium hydroxide is amphoteric, while the hydroxides of other elements in the same family are moderately alkaline or strongly alkaline. Beryllium salts are strongly hydrolyzed to form tetrahedral ions. Beryllium-oxygen bond is very strong, which weakens the hydrogen-oxygen bond, so hydrated beryllium ions are easy to lose protons. So beryllium salt is acidic in pure water. However, the salts of other elements in the same family (except magnesium) have no hydrolysis.
Beryllium oxide can be obtained by burning beryllium in oxygen or decomposing beryllium carbonate, beryllium nitrate and beryllium hydroxide by heating. Its melting point is 2803K, and it is insoluble in water and ethanol, so it can be used as a high temperature resistant material. Beryllium oxide is a valence compound, which is composed of molecules and has a zinc sulfide (sphalerite type) structure of 44. Beryllium oxide is insoluble in water, but can be dissolved in acid to form beryllium salt, and can also be dissolved in alkali to form beryllium salt, so beryllium oxide is amphoteric oxide.
Beryllium hydroxide is a white solid which is almost insoluble in water. It is an amphoteric hydroxide, which is soluble in acid to form beryllium salt and soluble in alkali to form beryllium salt.
Beryllium chloride is produced by burning beryllium in chlorine, which is a valence compound. Beryllium chloride can sublimate and is not conductive. The molecule of anhydrous beryllium chloride consists of two beryllium atoms and four chlorine atoms: 2Be+2Cl2= ignition =Be2Cl4.
Beryllium reacts with sulfur to produce beryllium sulfide, which is gray powder with a density of 2360 kg/m3.
Beryllium powder reacts with high-quality graphite powder to generate organic compound beryllium carbide, which is a yellow-red solid and decomposes into methane when it meets water.
Because beryllium is an electron-deficient atom and its halide is Lewis acid, it is easy to form complexes or adducts with electron pair donors. Therefore, beryllium can form many complexes. Beryllium compounds are extremely toxic because of their high solubility and easy formation of complexes.
Beryllium and aluminum have many similar chemical properties, but their physiological functions in human body are quite different. Aluminum will not cause acute poisoning or cancer, but beryllium is very toxic to human body. Inhaling a small amount of beryllium oxide is fatal.
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