Substance composed of atoms, each of which has the same atomic number (Z) and chemical properties. The chemical properties of an element are determined by the arrangement of the electrons in the various shells (specified by their quantum number) that surround the nucleus. In a neutral atom, the number of that tends to be concentrated in the The most abundant group of minerals in Earth's crust, the structure of silicates are dominated by the silica tetrahedron, SiO44-, with metal ions occurring between tetrahedra). The mesodesmic bonds of the silicon tetrahedron allow extensive polymerization and silicates are classified according to the amount of linking that occurs between the phase, e.g., B, O, halogens, Large divalent (2+) elements in the second column (from the left) of the periodic table: Be, Mg, Ca, Sr, and Ba. These elements are less reactive than the alkali metals and have higher melting points and boiling points. They are generally white, differing by shades of color or casts and, alkali metals, Al, Si, Sc, Ti, V, Cr, Mn, Y, Zr, Nb, Often abbreviated as “REE”, these 16 elements include (preceded by their atomic numbers): 21 scandium (Sc), 39 Yttrium (Y) and the 14 elements that comprise the lanthanides excluding 61 Promethium, an extremely rare and radioactive element. These elements show closely related geochemical behaviors associated with their filled 4f atomic orbital., Hf, Ta, W, Th, and U.