Alkaline earth metal salts are less soluble in water than the corresponding alkali metal salts,because Alkaline earth metal cations possess high lattice energy due to their smaller size and higher charge. Atomic size increases as we move down the alkali group. J K CET 2016: The alkaline earth metal sulphate which is most soluble in water among the following is (A) BaSO4 (B) CaSO4 (C) SrSO4 (D) BeSO4 . Therefore, alkali metals are highly reactive and are not found in nature in their elemental state. The heavier alkaline earth metals react more vigorously than the lighter ones. The sodium metal, which is discharged at cathode, combines with mercury to form an amalgam. As a result, it forms hydrated salts such as LiCl.2 H2O. b) It is used in concrete and reinforced concrete . ( c ) It is used as a flux during the smelting of iron ores. . (a) Nitrates (b) Carbonates (c) Sulphates. Hence, they usually do not form hydrated salts. The alkaline earth metalsare all of the elements in the second column (column 2A) of the periodic table. Hence option A is correct. The atomic size of sodium and potassium is larger than that of magnesium and calcium. Molten sodium is taken out of the cell and collected over kerosene. LiF is insoluble in water. (ii) BaO is soluble but BaSO4 is insoluble in water. Therefore, they cannot be obtained by chemical reduction of their oxides. Why? It reacts with acid as well as bases. (iii) Chemically, plaster of Paris is 2CaSO4.H2O. Alkaline earth metals forms salts of oxoacids, which include carbonates, sulphates and nitrates. Hydroxide salts of Group II components (Ca, Sr, and Ba) are marginally solvent. Q-6. M + (x+y) NH3 → [ M (NH3) x ] + + [ e (NH3) y ] _. General characteristics of alkaline earth metals are as follows. (i) Both Li and Mg react slowly with cold water. Reactions in Water. It is used in building industry as well as in plaster . Hence, they can easily lose electrons. When an alkaline earth metal is heated, the valence electrons get excited to a higher energy level. Alkaline earth metal peroxides have been described as delayed gel breakers in alkaline aqueous fluids containing hydroxypropyl guar (Mondshine, 1993). When BeO is dissolved in water, the hydration energy of its ions is not sufficient to overcome the high lattice energy. Step 4: NaHCO3 is heated strongly to convert it into Na2CO3. Sodium is liberated at the anode while Cl2 is evolved at cathode. Therefore, BeO is insoluble in water. the colour changes to bronze .The blue colour of alkali metals is due to ammoniated electrons . (iv) Neither Li nor Mg form peroxides or super-oxides. Alkali and Alkaline Earth Metals. Alkaline-earth metal, any of the six chemical elements that comprise Group 2 of the periodic table. How would you explain the following observations? The alkaline earth metals are the elements that correspond to group 2 of the modern periodic table. All the alkaline earth metals except beryllium also react with water to form strongly alkaline hydroxides which should be handled with great care. The balanced chemical equation for the reaction between Na2O2and water is: When KO2 reacts with water , it forms hydrogen peroxide and oxygen. (a) Mg helps in relaxing nerves and muscles. is more soluble than the others. Among the given metals, Cs is the largest and has the least melting point. Alkali Metals And Earth Alkaline Metals General Properties. The stability of sulphates of alkaline earth metals increases as the electropositive character of the metal increases. Beryllium and magnesium do not give colour to flame whereas other alkaline earth metals do so. Completing the CAPTCHA proves you are a human and gives you temporary access to the web property. Potassium, and Cesium have much lower ionisation enthalpy than that of Lithium .Therefore ,these metals on exposure to light easily emit electrons but Lithium does not . Also, it has the highest charge density and highest polarising power. Carbonates formed by alkaline earth metals are insoluble in water however, precipitate is formed when sodium or ammonium carbonate solution is added. Alkaline earth metals hydroxides are less soluble in water as compared to alkali metals. The nitrate salts tend to be soluble, but the carbonates and sulfates of the heavier alkaline earth metals are quite insoluble because of the higher lattice energy due to the doubly charged cation and anion. When added to water, the first alkaline earth metal, (Beryllium), is totally nonreactive, and doesn't even react with steam. The size compatibility of Be 2+ and O 2 is high. Lithium, sodium, potassium, rubidium, cesium and Francium are called alkali metals because they react with water to give alkali. As a result , the hydroxides and carbonates of sodium and potassium are easily soluble in water whereas the corresponding salts of magnesium and calcium are sparingly soluble in water . . (b) alkali metals are prepared by electrolysis of their fused chlorides ? (a) It is used in plastering and in construction of building , bridges and dams etc. Please enable Cookies and reload the page. Why are lithium salts commonly hydrated and those of the other alkali metal ions usually anhydrous? As a result, the binding energies of their atoms in the crystal lattice decrease. In the reaction, A is 1) BeO 2) 3) … (i) When Na metal is dropped in water, it reacts violently to form sodium hydroxide and hydrogen gas. As a result, water molecules get attached to lithium salts as water of crystallization. Sodium sulfide. These elements therefore do not give any colour in Bunsen flame . Magnesium carbonate, for example, has a solubility of about 0.02 g per 100 g of water at room temperature. (iii) LiI is more soluble than KI in ethanol. Similarities between lithium and magnesium are as follows. Since fluoride ion is much smaller in size than chloride ion, the lattice energy of LiF is greater than that of LiCl. So, both assertion and reason are correct and reason is the correct explanation for assertion. The carbonates and sulphates of alkaline earth metals are less soluble than corresponding alkali metals . Comment on each of the following observations: (b) Lithium is the only alkali metal to form a nitride directly. Because of these factors, the outermost electron in potassium can be lost easily as compared to sodium. These questions will build your knowledge and your own create quiz will build yours and others people knowledge. The ammoniated electrons absorb energy corresponding to red region of visible light. in solid state BeCl2 exists as a polymeric structure with chlorobridges . Answer : Beryllium forms amphoteric oxide BeO . Therefore, the oxidation sate of sodium is +1. 41. Therefore, hydrated Li + is the least mobile and hydrated Cs + is the most mobile. ... Water-soluble salts that are carried over from the desalter. (iii)These metals have atomic and ionic radii smaller than that of alkali metals. Also, the electropositive character increases on moving down the group from Be to Ba. On the other hand ,nitrates of alkaline earth metals are soluble in water .However , their solubility decreases down the group because their hydration enthalpies decreases more rapidly than the lattice enthalpies. This causes a decrease in the melting point. However , their stability increases as we move down the group . But due to instability of sulfide ion, sulfide ion can hydrolysis and emit hydrogen sulfide gas by giving strong aqueous solution. (vii) They are highly electropositive in nature. Hence, it attracts water molecules more strongly than the other alkali metals. The carbonates become less soluble down the group. 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