The S Block Elements

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The lewis structure of O₂^– ion is,

Oxygen atom having no charge has 6 electrons, so its oxidation number is zero. Oxygen atoms containing −1 charge have 7 electrons, so its oxidation number is −1. The average oxidation state of oxygen in this ion is, =1/2

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In the Solvay process, carbon dioxide is transferred through a concentrated solution of ammoniacontaining sodium chloride, which forms ammonium carbonate followed by ammonium hydrogen carbonate. The chemicals in ammonium hydrogen carbonate are different and are heated to form sodium carbonate. NH₃ is found in a solution containing NH₄Cl that is heated and treated with Ca (OH)₂? The reaction of (NH₄)2CO₃ with NaCl provides two products, Na₂CO₃ and NH₄Cl both soluble in water which do not shift to the right balance.

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Ionic compounds are formed from the alkali metals due to their large ionic size and low ionization enthalpy. Thus, they are soluble in water. But, due to the small ionic size, high ionization enthalpy, and high electronegativity of lithium, it forms compounds of covalent nature and thus, are soluble in organic solvents.

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BeSO₄ and MgSO₄ readily soluble in water while CaSO₄, SrSO₄ and BaSO₄ are insoluble The greater hydration enthalpy of Be²⁺ and Mg²⁺ ions overcome the lattice enthalpy factor and therefore, their sulfates are soluble.

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The element from group 2 is beryllium. Be (OH)₂ is amphoteric. It reacts with both acids and bases. It reacts with acid to form beryllium chloride and it reacts with base to form beryllate ion which is soluble in sodium hydroxide. The reaction is shown below.

Be (OH)₂+2OH−→ [Be (OH)₄]²⁻

Be (OH)₂+2HCl→BeCl₂+2H₂O

Beryllium sulfate are readily soluble in water.

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These two elements have similar properties because of their similar atomic and ionic radii.

(i) Both are lighter element and harder than the other metals in their respective groups.

(ii) The halides of both elements, LiCl and MgCl₂ are soluble in ethanol.

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(i) O₂²⁻+ 2H₂O → H₂O₂+2OH⁻

(ii) 2O₂⁻+2H₂O→2OH⁻+H₂O₂+O₂

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Alkali metals forms oxide when reacted with air. Lithium forms monoxide, sodium forms peroxide and potassium forms superoxide.

4Li+O₂→2Li₂O

Na+O₂→Na₂O₂

 K+O₂→KO₂

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Lithium has the highest negative reduction potential value. Due to the small size of lithium it has the highest ionization enthalpy. Due to this, the reducing power of lithium is the highest in an aqueous solution.