Chemical impact on chrystal structure of the second-group metals

Under the atmospheric pressure and standard temperature, alkali metals crystallize isostructurally, but not in the form of close packing. They have a body-centered cubic unit cell. No structural isomorphism is observed in crystal structures of group 2 metals. As atomic number of group 2 metals increases, their crystal structures change. The lightest metals, beryllium Be and magnesium Mg, are crystallized in the form of hexagonal close-packed structure, whereas calcium Ca and strontium Sr exhibit face-centered cubic unit cells. However, barium Ba and strontium Sr have body-centered structures, typical of alkali metals. Nowadays, there is no any unified explanation of what causes the lack of structural isomorphism in group 2 metals. The authors find some correlations explaining a reasonable crystalline structure expansion towards barium Ba and radium Ra. It is done by considering physical and chemical properties of group 2 metals, as well as dependences of atomic force characteristics on nucleus charge, atomic, and ionic radii. There are examples showing a correlation between changes in physical and chemical properties and crystalline structures of group 2 metals. The number of valence sp-electrons is necessary but not sufficient for choosing a crystallization mode.

References

[1] Baur W.H. One Hundred Years of Inorganic Crystal Chemistry - a Personal View. Crystallography Reviews, 2014, vol. 20, iss. 2, pp. 64-116.

[2] Watkin D.J. Chemical Crystallography-Science, Technology or a Black Art. Crystallography Reviews, 2010, vol. 16, iss. 3, pp. 197-230. D0I:10.1080/08893110903483246

[3] Godovikov A.A. Kristallokhimiya prostykh veshchestv [Crystal chemistry of elements]. Novosibirsk, Nauka Publ., 1979.

[4] Urusov V.S., Eremin N.N. Kristallokhimiya [Crystal chemistry]. Moscow, MGU im. M.V. Lomonosova Publ., 2010, 256 p.

[5] Egorov-Tismenko Yu.K. Kristallografiya i kristallokhimiya [Crystallography and crystal chemistry]. Moscow, KDU Publ., 2005. 592 p.

[6] Bek P., ed. Elektronnaya struktura perekhodnykh metallov i ikh splavov [Electronic structure of transition metals and their alloys]. Moscow, Metallurgiya Publ., 1966, pp. 211-224.

[7] Engel N. Kem. Maanedsblad, 1949, vol. 5-6, pp. 8-10.

[8] Godovikov A.A. Periodicheskaya sistema D.I. Mendeleeva i silovye kharakteristiki elementov [Mendeleev’s periodic system of chemical elements and power characteristics of elements]. Novosibirsk, Nauka Publ., 1981, iss. 480.

[9] Lur’e Yu.Yu. Spravochnik po analiticheskoy khimii [Reference book on analytical chemistry]. Moscow, Al’yans Publ., 2007. 447 p.

[10] Gurtov V.A., Osaulenko R.N. Fizika tverdogo tela dlya inzhenerov [Solid state physics for engineers]. Moscow, Tekhnosfera Publ., 2012, 558 p.

[11] Kittel’ Ch. Vvedenie v fiziku tverdogo tela [Introduction to solid state physics]. Moscow, Tekhn.-Teor. Lit. Publ., 1957. 524 p.

[12] Abrikosov A.A. Osnovy teorii metallov [Fundamentals of metals]. Moscow, Fizmatgiz Publ., 2009. 600 p.