The S Block Elements
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New answer posted
4 months agoContributor-Level 10
This is a long answer type question as classified in NCERT Exemplar
The element imparts yellow colour to the flame in flame test which means the element of group 1 is sodium. Sodium is used in the transmission of nerve signals and transport of sugars and amino acids into cells. Reactions are shown below.
2Na+O2→Na2O2
4Na+O2→2Na2O
2Na2O+O2→2Na2O2
New answer posted
4 months agoContributor-Level 10
This is a long answer type question as classified in NCERT Exemplar
In group 2, only beryllium is amphoteric in nature which means it reacts with both acids and bases. Also, beryllium only forms covalent oxide due to the covalent nature. So, the element is beryllium.
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
New answer posted
4 months agoContributor-Level 10
This is a long answer type question as classified in NCERT Exemplar
Beryllium being least reactive does not form hydride by direct heating with dihydrogen. It is prepared by reacting it with lithium aluminum hydride. The reactions are shown below.
8LiH + Al2Cl6→2LiAlH4+6LiCl
2BeCl2+LiAlH4→2BeH2+LiCl+AlCl3
New answer posted
4 months agoContributor-Level 10
This is a long answer type question as classified in NCERT Exemplar
Compound A reacts with water to form compound B. So, the compound A is calcium oxide. When water is added to calcium oxide, calcium hydroxide is formed. It is lime water. The compound gives a milky appearance which is compound C. The compound C is calcium carbonate. On passing, excess carbon dioxide milkiness disappears due to the formation of compound D. The compound is calcium hydrogen carbonate. The reactions are as follows:
CaO+H2O→Ca (OH)2
Ca (OH)2+CO2→CaCO3
Ca (OH)2+CO2+H2O→Ca (HCO3)2
New answer posted
4 months agoContributor-Level 10
This is a long answer type question as classified in NCERT Exemplar
As the size of metal ions increases, the stability of peroxides and superoxides increases. Peroxide and superoxide ions combine with a large size of alkali metals. Lithium forms monoxide, sodium forms peroxide and potassium, rubidium and caesium forms superoxide.
Li+O2→Li2O
Na+O2→Na2O2
K+O2→KO2
New answer posted
4 months agoContributor-Level 10
This is a long answer type question as classified in NCERT Exemplar
(i) The alkali metals dissolve in liquid ammonia and give a blue solution, which is conductive in nature. A solution of sodium in liquid ammonia at -30C conducts electricity. The ammoniated electrons are responsible for the blue color of the solution as they absorb energy in the visible region of light and impart blue color to the solution. Both the ammoniated cations and ammoniated electrons are responsible for the electrical conductivity of the solution.
Na + (x+y)NH3→ [Na (NH3)x]+ + [e (NH3)y]−
(ii) The blue color changes to bronze color in concentrated solution
New question posted
4 months agoNew answer posted
4 months agoContributor-Level 10
This is a long answer type question as classified in NCERT Exemplar
(i) Alkaline earth metal compounds are less ionic than alkali metals because of small size and more effective nuclear charge.
(ii) Oxides of alkali metals are more basic than alkaline earth metals. This are water soluble and highly exothermic. The hydroxides of alkaline earth metals are less basic than alkali metals.
(iii) Alkaline earth metals give oxosalts. The reactivity of alkali metals is faster than the reactivity of alkaline earth metal. The reactivity of alkaline earth metal is less due to small size and more effective nuclear charge.
(iv) The oxo salts of alka
New answer posted
4 months agoContributor-Level 10
This is a long answer type question as classified in NCERT Exemplar
Alkali metals are ionic in nature due to their larger size. They have +1 oxidation states. Alkali metals forms three types of oxides such as peroxides, superoxides and normal oxides. The basic character of normal oxides increases from lithium oxide to caesium oxide.
The halides of alkali metals are also ionic except lithium halide. Lithium halide is covalent in nature because of small size and high polarizing power.
Oxosalts of alkali metal are solid water-soluble ionic compounds. Oxosalts of lithium show different properties due to small size of lithium.
New answer posted
4 months agoContributor-Level 10
All the compounds are crystalline solids and their solubility in water is guided by both lattice enthalpy and hydration enthalpy. In case of sodium and potassium compounds, the magnitude of lattice enthalpy is quite small as compared of sodium and potassium that are mentioned, readily dissolve in water. However, in case of corresponding magnesium and calcium compounds, the cations have smaller sizes and more magnitude of positive charge. This means that their lattice enthalpies are more as compared to the compounds of sodium and potassium. Therefore, the hydroxides and carbonates of these metals are only sparingly soluble in water.
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