The high solubility of BeSO4 and MgSO4  is due to the high hydration enthalpy because of smaller size of Be2+ and Mg2+ ions. The increased stability of slab structures (both From the theoretical point of view, Ca2+ is larger than Mg2+, so we can expect ionic size effects to play an important role in determining structural differences. For (BaO)3, again, two different structures are obtained. While in bulk this is negligible for MgO, a reduction in the bond lengths in clusters could be responsible for the increased covalent character. The alkaline earth metals burn in oxygen forming the ionic oxides of the type where stands for alkaline earth metals except which form peroxide. alkaline earth metal hydroxides are less soluble in water, basic strength of hydroxides increases down the group, preparation and properties of sulphates of alkaline earth metals, preparation of halides of alkaline earth metal, properties of halides of alkaline earth metal, properties of hydroxides of alkaline earth metals, stability and uses of alkaline earth metals, NCERT Solutions for Class 10 हिन्दी – क्षितिज – Chapter 3 – सवैया, कवित्त – देव, NCERT Solutions for Class 10 हिन्दी – क्षितिज – Chapter 2 – राम लक्ष्मण परशुराम संवाद, NCERT Solutions for Class 10 हिन्दी – क्षितिज – Chapter 1 – पद, Economics Chapter 5 Consumer Rights – Notes & Study Material. (ii) All the alkaline earth metals form oxides of formula MO. The bond lengths and total energy per molecule for the lowest energy structures are given in Table 5. This happens at the expense of the p orbital population, so that the overall charge on the metal ion remains close to +1. The temperature of decomposition i.e. It can be seen from Figure 8 that the involvement of d orbitals increases with increasing atomic number of the metal ion. In view of the fact that the metal and oxygen charges are close to +1 and −1, respectively, the actual ionic radii are expected to lie between those for the neutral state and the divalent ions. However, it may be noted that the energy differences are not very large for this stoichiometry. In the hexagonal structure, the O–O distance is 3.45 Å, compared to 2.86 Å for the rectangular cluster. The GGA-PW91 values are similar, although the computed Mg–O bond distance is much larger (1.843 Å), reflecting the tendency of GGA to underbind atoms. All the carbonates of alkaline earth metal are more soluble in the presence of CO2 due to the formation of corresponding bicarbonates. For (CaO)3, however, it was found that both initial structures optimized to different geometries. Complete geometry optimizations for all structures [ M = Be, Mg, Ca, Sr, Ba] Thus, hexagonal rings are slightly more stable than the slab-shaped structures in the case of The shortest Sr–O bond distances are the outer ones, that is, between two 2-coordinate sites (2.107 Å), and the corresponding bond order is 1.128, while the longest bond is the central In this case, three structures, namely, slab, hexagonal, and ladder, were studied (Table 4). Stability: The carbonates of all alkaline earth metal decompose on heating to form corresponding metal oxide and carbon dioxide. All the bicarbonates of alkaline earth metal are stable only in solution and have not been isolated in the pure state. However, the results from such studies on alkaline earth metal oxides are contradictory and depend on the process of formation of the clusters. Metals having standard reduction potential near about -2.0 volt or more negative like alkali metals, alkaline earth metals are strongly electropositive in nature. In this work, we have performed a comparative study of the structures, stabilities, and properties of some alkaline earth metal oxides ( The fact that a small cation can stabilize a small anion and a large cation can stabilize a large anion explains the formation and stability of these oxides. We observe that the Mg–O bond distances in the terminal rings of (MgO)6 are reduced when going from the rhombic (slab) to the hexagonal structure from 1.919 Å in the former to 1.891 Å in the latter. (MgO)5. Nanocrystalline CaO is used as an absorbent to remove COD from paper mill effluent [12]. Stability of oxides decreases down the group. The bond length (1.743 Å) is, however, small. This structure has a high band gap (3.05 eV), which is much lower than that reported for bulk MgO [45–47]. The atomic and ionic radii of O and lattice O2− are 0.66 and 1.40 Å, respectively. Our earlier studies [22, 23] on the (MgO)12 cluster had indicated that the (MgO)12 nanotube, consisting of four stacked hexagonal (MgO)3 rings, is more stable than the bulk-like cubic structure by 0.48 eV. Besides, Ca2+ is approximately six times as polarizable as Mg2+, and the polarizabilities of the oxide anions are also larger in CaO because the bonding is weaker than in MgO. Alkali metal - Alkali metal - Chemical properties: Since the alkali metals are the most electropositive (the least electronegative) of elements, they react with a great variety of nonmetals. Sign up here as a reviewer to help fast-track new submissions. , the slab structure is still the preferred one, but to a lesser extent. For the other metal oxides, the slab structure is preferred. , For all (MO)4, the slab structures are preferred over the octagonal ring and ladder structures. For example - SO2, CO2, SO3, Cl2O7, P2O5, N2O5 etc Basic oxides are those which produces base on reacting with water and are mostly made up of metals such as Na2O, CaO, BaO Neutral oxides do not form salts on reacting with acid or bases. Prinka Batra, Ritu Gaba, Upasana Issar, Rita Kakkar, "Structures and Stabilities of Alkaline Earth Metal Oxide Nanoclusters: A DFT Study", Journal of Theoretical Chemistry, vol. While much progress has been made on clusters of metals and semiconductors, metal oxide particles are often considered to be bulk fragments. The Mulliken charge on each oxygen is −0.915. For example, for (MgO)6, the ring and interplanar distances are 1.891 and 1.980 Å, respectively. The group replaced the sodium by other alkali or alkaline earth metals: calcium, strontium, and barium. Although both LDA and GGA indicate this preference, it is interesting to see that the optimized structures for the octagonal initial structure are different for the two cases (Figure 3(b)) and different from the initial ring structure, unlike the case of (MgO)4 (Figure 3(a)). The thermal stability of alkali and alkaline-earth metal hydroxide—nitrate systems has been investigated by thermal analysis, voltammetry and observation with a high-temperature microscope. This signifies increased size of the oxygen ion in the system relative to the oxygen atom. The (MO)6 system is the first system for which both the slab structure and the hexagonal structure are possible, and we can make a comparison of the two. The temperature of decomposition of these sulphates increases as the electropositive character of the metal or the basicity of the metal hydroxide increases down the group. 2Ca + O 2 → 2CaO. 1) The cations of group V of qualitative analysis are precipitated as their insoluble carbonates from the solution of their soluble salts by adding (NH4)2CO3 in presence of NH4Cl and excess of NH4OH. , whereas the opposite is true for Figure 1 gives the optimized structures for all the (MO)2 moieties. P. N. Kapoor, A. K. Bhagi, R. S. Mulukutla, and K. J. Klabunde, A. Khaleel, P. N. Kapoor, and K. J. Klabunde, “Nanocrystalline metal oxides as new adsorbents for air purification,”, J. Heyd, J. E. Peralta, and G. E. Scuseria, “Energy band gaps and lattice parameters evaluated with the Heyd-Scuseria-Ernzerhof screened hybrid functional,”, S. Utamapanya, K. J. Klabunde, and J. R. Schlup, “Nanoscale metal oxide particles/clusters as chemical reagents,”, O. Koper, Y. X. Li, and K. J. Klabunde, “Destructive adsorption of chlorinated hydrocarbons on ultrafine (nanoscale) particles of calcium oxide,”, Y. X. Li and K. J. Klabunde, “Nano-scale metal oxide particles as chemical reagents. Similarly, the MgO-I and MgO-II starting structures optimize to the same geometry, which is a hybrid of one hexagonal ring fused with two four-membered rings. Ions with greater atomic mass (right) would increase ZT as they suppress thermal conductivity in the cobalt oxide layers (Yugo Takashima et al, Journal of Materials Chemistry A, October 13, 2020). An alternate explanation for the preference for the six-membered ring structure in the case of MgO could be the existence of aromaticity. The atomic positions were relaxed to achieve minimum energy, until the system energy converged to 2 × 10−5 Ha and the gradient to 0.004 Ha Å−1. Barium oxide is an oxide with interesting electronic and structural properties. were carried out. Similarly, the computed Mg–O bond lengths are 1.743, 1.767, and 1.756 Å, respectively, for LDA-PWC, GGA-PW91, and B3LYP [40, 41] calculations in comparison with the experimental [30, 31, 43] value of 1.749 Å. Alkaline earth metal carbonates have less stability towards heat and decompose to carbon dioxide. As for the ladder structures, the bond distance in the inner ring of the three-ring slab cluster (2.123 Å) is markedly elongated as compared to the terminal bond distance. Copyright © 2013 Prinka Batra et al. However, the energy differences are too small for one to make a definite statement regarding the relative stabilities. The LDA result is far superior to the other calculations, although its tendency to overbind is clear from the result. Thermal stability increases with the increase in the size of the cation present in the carbonate. MgCO 3 < CaCO 3 < SrCO 3 < BaCO 3. are 0.915, 1.055, −0.952 and −0.981, respectively. The results of the experimental studies and our calculations can be reconciled if we assume that the neutral stoichiometric and The computed electron configuration of the magnesium ion differs from the expected 2p6. Two distinctly different interplanar distances (1.936 Å and 1.898 Å) are also observed, depending on which atom, Mg or O, sits on the terminal ring of the three-ring stack. For this reason, only the optimized structures for (SrO)4 are shown in Figure 3(c). Well-known sodium-cobalt oxide, where sodium and cobalt oxide layers alternate, shows a very low ZT of around 0.03, but the material developed by Ohta’s group achieved a ZT of 0.11. For (SrO)3, the ladder structure is preferred by 0.16 eV. Alkaline earth metal nitrates are prepared in solution and can be crystallized as hydrated salt by the action of HNO3 on oxides ,hydroxides and carbonates. 3) CaCO3 is used in Solvay – ammonia process for manufacture of Na2CO3 , in glass making and in cement manufacture. For CaO, the slab structure is again preferred. The Mulliken charges on the atoms show a behavior similar to that observed for (CaO)3 and (SrO)3; that is, the charges on Going to Simple ionic models based on phenomenological pair potentials have been used to explain the global trends found in these experiments [17–20]. Indeed, the participation of d orbitals increases from 0.263 in the terminal atoms of the MgO slab to 0.406 in CaO, 0.715 in SrO, and 0.835 for BaO. The optimized M–O bond distances are slightly closer to the gas phase values than to the ionic values. Our calculations employed numerical basis sets of double-ζ quality plus polarization functions (DNP) to describe the valence orbitals. The energy differences are higher for this case, and the slab form is more emphatically preferred. In this method, negative NICS values indicate aromaticity and positive values antiaromaticity. The Mulliken charges on the atoms show a behavior similar to that observed for (CaO)3; that is, the charges on An explanation based on simple packing arguments has been proposed to explain the variation in relative stabilities. The ladder structure is slightly preferred (by 0.12 eV; see Table 1). Strontium and barium nitrate are used in pyrotechnics for giving red and green flames. We therefore first compared results for the MgO molecular form obtained by different methods with the experimental quantities. , , for which the hexagonal ring-based structures turn out to be more stable), in agreement with previous studies [29, 32, 40, 41]. The reported binding energy values were corrected for zero-point vibrational energies. Stability of carbonates increases down group I (alkali) and group II (alkaline earth) metals. Thus, experimental knowledge of abundance of masses alone cannot distinguish between the two structures, and sophisticated calculations such as the present ones can only decide the relative stabilities. An interesting trend is also observed. The solubility of carbonates of alkaline earth metal decreases down the group mainly due to decreasing hydration enthalpies of the cations from Be2+ to Ba2+ . For (SrO)5 (Figure 4(c)) and (BaO)5 (Figure 4(d)), the ladder structures are preferred, and the chair structures could not be optimized. The 3s, 3p, and 3d orbitals are occupied, leading to a formal charge on Mg closer to one than the expected two. The corresponding gas phase values [43] for the diatomic species are 1.749, 1.822, 1.920, and 1.940 Å, respectively. Thermal stability: Increases down the group like carbonates BeSO 4 Mg > > Ca > Sr > Ba down group I ( alkali ) and ii! Hexagonal-Ring-Based structure is 2.3 eV, that of lithium decompose on heating, forming an oxide and dioxide. 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