Alkaline earth metals Group cations formed

Thus, alkaline earth metals (group 2) form cations (M ) with less ease compared to the alkali metals (group 1). 

The elements that form only one cation are the alkali metals (group IA), the alkaline earth metals (group IIA), zinc, cadmium, aluminum, and most often silver. The charge on the ions that these elements form in their compounds is always equal to their periodic table group number (or group number minus 10 in the newest labeling system in the periodic table). 

Zintl phases remarks on their definition. We have seen that the Zintl phases may be considered as a group of compounds formed by an electropositive (cationic) component (alkali, alkaline earth metal, lanthanide) and an anionic component (for instance a main group element of moderate electronegativity). The anionic part of the structure may be described in terms of normal valence combination. 

The conclusions from this analysis of carboxylate—metal binding in small structures studied to high resolution are (1) The metal cation generally lies in the plane of the carboxyl group. There are some notable exceptions. Alkali metals and some alkaline earth metals, which ionize readily and form strong bases, appear to have less specific locations of binding. (2) If the distance lies in the range 2.3-2.6 A, it is... 

The formation of the merocyanine form 119 can be induced by addition of heavy metal cations (Pb, La, Eu, Tb ) to a solution of a spirooxazine 118 containing a crown ether group in the B-ring (Equation 1). The chelation occurs first to the crown ether and then to the negatively charged oxygen. In contrast, 118 does not react upon addition of alkaline earth metal cations (Mg, Ca, Ba ) <2005JP0504>. 

The term Zintl phase is applied to solids formed between either an alkali- or alkaline-earth metal and a main group p-block element from group 14, 15, or 16 in the periodic table. These phases are characterized by a network of homonuclear or heteronuclear polyatomic clusters (the Zintl ions), which carry a net negative charge, and that are neutralized by cations. Broader definitions of the Zintl phase are sometimes used. Group 13 elements have been included with the Zintl anions and an electropositive rare-earth element or transition element with a filled d shell (e.g. Cu) or empty d shell (e.g. Ti) has replaced the alkali- or alkaline-earth element in some reports. Although the bonding between the Zintl ions and the cations in the Zintl phases is markedly polar, by our earlier definition those compounds formed between the alkali- or alkaline-earth metals with the heavier anions (i.e. Sn, Pb, Bi) can be considered intermetallic phases. 

Naming the constant type of cation involves naming the element and adding the word ion, unless a compound is being named. For example, is the potassium ion, and Ca is the calcium ion KCl is potassium chloride. The alkali metals, the alkaline earth metals, zinc, cadmium, aluminum, and silver are the most important metals that form ions of the constant type (Figure 6.2). Each of these metals forms the same ion in any of its compounds, and the charge on the ion is equal to the classical periodic group number. 

Reaction of group 15 elements like arsenic with alkali or alkaline earth metals forms Zintl anions of the general type Asn". Characterization of these species has been accomplished dissolving the solids in liquid NH3 or ethylenediamine (H2NCH2CH2NH2) and adding the macrocycle, 2,2,2-crypt (5) to complex the cations and stabilize the polyatomic anions. The fully characterized Zintl arsenic anions As4, As and Asu are shown inFigme 1. ... 

All of the alkaline earth metals form saltlike MX2 dihahdes (see Alkaline Earth Metals Inorganic Chemistry). Within this group, we observe stmctural effects owing to both cation sizes and properties of the halide ions. From Be to Ba, coordination numbers monotonically increase from four (tetrahedral) in Be dihalides to eight (cubic) or nine (tricapped trigonal prismatic) in the Ba systems. 

The Group 2A elements (with the valence electron configuration ns2) are very reactive, losing their two valence electrons to form ionic compounds that contain M2+ cations. These elements are commonly called the alkaline earth metals because of the basicity of their oxides ... 

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