Alkaline earth group oxidation number

The Guerbet reaction is an important industrial process for increasing the carbon numbers of alcohols. Thus, a primary or secondary alcohol reacts with itself or another alcohol to produce a higher alcohol (Scheme 23). Alkaline earth metal oxides have been used as catalysts for the condensation of alcohols. Ueda et al. (158,159) reported the condensation of methanol with other primary or secondary alcohols having a methyl or methylene group at the )S-position they used MgO, CaO, and ZnO as catalysts. The reactions were performed with gas-phase reactants at 635 K only MgO was found to be both active and selective (>80%). 

Figure 15.8 shows the formulas of a number of oxides of the representative elements in their highest oxidation states. Note that all alkali metal oxides and all alkaline earth metal oxides except BeO are basic. Beryllium oxide and several metallic oxides in Groups 3A and 4A are amphoteric. Nonmetallic oxides in which the oxidation number of the representative element is high are acidic (for example, N2O5, SO3, and CI2O7), but those in which the oxidation number of the representative element is low (for example, CO and NO) show no measurable acidic properties. No nonmetallic oxides are known to have basic properties. 

In its compounds, the oxidation number of every alkali metal and alkaline earth metal is equal to its group number. 

Symbol Be atomic number 4 atomic weight 9.012 a Group IIA (Group 2) metal the lightest alkaline-earth metallic element atomic radius l.OOA ionic radius (Be2+) 0.30A electronic configuration Is22s2 ionization potential, Be 9.32eV, Be + 18.21 eV oxidation state +2... 

B Because they have an oxidation number of 2+ when they form ions, the alkaline earth metals (elements in group 2) will take on two chlorine ions to form chloride salts. 

In relation to the surface defects on the group II alkaline earth oxides, EPR has been instrumental in unraveling the electronic structure of the defects on both polycrystalline and well defined single crystal surfaces. These trapped electron centers can be formed in a number of different ways. The most convenient means on powders is by exposure of the alkaline earth oxide, such as MgO, to hydrogen atoms [22]. Spontaneous ionization of the H atoms occurs with the subsequent formation of excess electrons on the surface ... 

---