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Unlike the other group 2 metals, beryllium does not react with hydrogen. [3] Instead, BeH 2 is prepared from preformed beryllium(II) compounds. It was first synthesized in 1951 by treating dimethylberyllium, Be(CH 3) 2, with lithium aluminium hydride, LiAlH 4. [4] Purer BeH 2 forms from the pyrolysis of di-tert-butylberyllium, Be(C[CH 3] 3) 2 ...
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β 2 microglobulin (B2M) is a component of MHC class I molecules. MHC class I molecules have α 1 , α 2 , and α 3 proteins which are present on all nucleated cells (excluding red blood cells ). [ 5 ] [ 6 ] In humans, the β 2 microglobulin protein [ 7 ] is encoded by the B2M gene .
The concentration of the first hydrolysis product, [Be(H 2 O) 3 (OH)] +, is less than 1% of the beryllium concentration. The most stable hydrolysis product is the trimeric ion [Be 3 (OH) 3 (H 2 O) 6] 3+. Beryllium hydroxide, Be(OH) 2, is insoluble in water at pH 5 or more. Consequently, beryllium compounds are generally insoluble at biological pH.
For example, manganese (Mn) has configuration 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 5; this is abbreviated to [Ar] 4s 2 3d 5, where [Ar] denotes a core configuration identical to that of the noble gas argon. In this atom, a 3d electron has energy similar to that of a 4s electron, and much higher than that of a 3s or 3p electron.
The least stable is 10 He, with half-life 260(40) yoctoseconds (2.6(4) × 10 −22 s), though 2 He may have an even shorter half-life. In Earth's atmosphere, the ratio of 3 He to 4 He is 1.343(13) × 10 −6. [5] However, the isotopic abundance of helium varies greatly depending on its origin.
Nitrogen dioxide is a reddish-brown gas with a pungent, acrid odor above 21.2 °C (70.2 °F; 294.3 K) and becomes a yellowish-brown liquid below 21.2 °C (70.2 °F; 294.3 K). It forms an equilibrium with its dimer , dinitrogen tetroxide ( N 2 O 4 ), and converts almost entirely to N 2 O 4 below −11.2 °C (11.8 °F; 261.9 K).
A period 2 element is one of the chemical elements in the second row (or period) of the periodic table of the chemical elements.The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases; a new row is started when chemical behavior begins to repeat, creating columns of elements with similar properties.