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The helium dimer can be formed in small amounts when helium gas expands and cools as it passes through a nozzle in a gas beam. [2] Only the isotope 4 He can form molecules like this; 4 He 3 He and 3 He 3 He do not exist, as they do not have a stable bound state. [6]
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 ...
Helium's first ionization energy of 24.57 eV is the highest of any element. [2] Helium has a complete shell of electrons, and in this form the atom does not readily accept any extra electrons nor join with anything to make covalent compounds. The electron affinity is 0.080 eV, which is very close to zero. [2]
The species [Be 3 O(H 2 PO 4) 6] 2-is notable for having a 3-coordinate oxide ion at its center. Basic beryllium acetate, Be 4 O(OAc) 6, has an oxide ion surrounded by a tetrahedron of beryllium atoms. With organic ligands, such as the malonate ion, the acid deprotonates when forming the complex. The donor atoms are two oxygens.
The excimers used for lasers may be noble gas dimers such as Ar 2, Kr 2 or Xe 2, or more commonly, the noble gas is combined with a halogen in excimers such as ArF, KrF, XeF, or XeCl. These lasers produce ultraviolet light, which, due to its short wavelength (193 nm for ArF and 248 nm for KrF), allows for high-precision imaging.
Helium-2, 2 He, is extremely unstable. Its nucleus, a diproton, consists of two protons with no neutrons.According to theoretical calculations, it would be much more stable (but still β + decay to deuterium) if the strong force were 2% greater. [18]
Mg 2+ Disodium phosphate is a very selective reagent for magnesium ions and, in the presence of ammonium salts and ammonia, forms a white precipitate of ammonium magnesium phosphate. Mg 2+ + NH 3 + Na 2 HPO 4 → (NH 4)MgPO 4 + 2Na + Ca 2+ Ca 2+ forms a white precipitate with ammonium oxalate. Calcium oxalate is insoluble in water, but is ...
Beryllium hydroxide, Be(OH) 2, is an amphoteric hydroxide, dissolving in both acids and alkalis.Industrially, it is produced as a by-product in the extraction of beryllium metal from the ores beryl and bertrandite. [7]