RBSE Class 11 Chemistry Notes Chapter 10 The s-Block Elements

These comprehensive RBSE Class 11 Chemistry Notes Chapter 10 The s-Block Elements will give a brief overview of all the concepts.

Rajasthan Board RBSE Solutions for Class 11 Chemistry in Hindi Medium & English Medium are part of RBSE Solutions for Class 11. Students can also read RBSE Class 11 Chemistry Important Questions for exam preparation. Students can also go through RBSE Class 11 Chemistry Notes to understand and remember the concepts easily.

RBSE Class 11 Chemistry Chapter 10 Notes The s-Block Elements

→ Alkali Metals: First group of s-block elements is known as alkali metals because their oxides gives strong base on mixing with water.

→ Physical Properties of Alkali Metals:

  • Li < Na Li+ < Na+ < K+ + <Fr+ (Ionic radius)
  • Li > Na > K > Rb> Cs > Fr (Ionisation energy)
  • Li < Na < K < Rh < Cs < Fr (Electropositive character) Li> Na > K > Rb > Cs > Fr (Electronegativity)
  • Li > Na > K > Rb > Cs > Fr (Boiling and Melting Points)
  • Na < K < Rb < Cs < Li (Reducing properties)
  • Li+ > Na+ > K+ > Rb+ > Cs+ (Hydration energy)

→ Polarisation: Distortion of electron cloud of anion due to cation is called polarisation.

→ Fajan’s Rule: According to the rule, polarization will be increased by:

  • High charge and small size of the cation.
  • High charge and large size of the anion.
  • The polarizability of an anion is related to the deformability of its electron cloud (i.e., its “softness”).
  • An incomplete valence shell electron configuration. Noble gas configuration of the cation produces better shielding and less polarizing power.

→ Soda Ash: Anhydrous sodium carbonate is called soda ash because it is found in ash of some aquatic plants.

→ Washing Soda: Sodium carbonate is called washing soda because it is used in washing clothes.

→ Baking Soda: Sodium bicarbonate is called baking soda. 

→ Caustic Soda: Sodium hydroxide is called caustic soda:

→ Alkaline Earth Metals: Group 2 of s-block elements is known as alkaline earth metals because their hydroxides are strong alkali (just like those of alkali metals) and these all are found in earth crust.

→ Milk of Magnesia: When magnesium is heated with boiled water or steam, it forms magnesium hydroxide. This is known as “Milk of Magnesia”.

RBSE Class 11 Chemistry Notes Chapter 10 The s-Block Elements

→ Properties of Alkaline Earth Metals

  • Be < Mg < Ca < Sr < Ba < Ra (Atomic radius)
  • Be2+ < Mg2+ < Ca2+ < Sr2+ < Ba2+ (Ionic radius)
  • Be < Mg
  • Be2+ < Mg2+ < Ca2+ < Sr2+ < Ba2+ (Hydration energy)

→ Magnelium: It is an alloy which has 95% Al, and 5% Mg. It is used in making aircraft parts, making piston of engines etc. 

→ Electron Metal: It is an alloy which has 95% Mg, and 5% Zn. It is used in making aircraft parts.

→ Duralumin: It is an alloy which has 95% Al, 0.5% Mg, and 4% Cu. lt is used for making parts of ship.

→ General Characteristics off Compounds off Alkaline Earth Metals

  • BeO < MgO < CaO < SrO < BaO (Alkaline strength)
  • Be(OH)2 < Mg(OH)2 < Ca(OH)2 < Sr(OH)2 < Ba(OH)2 (Alkaline strength)
  • BeCO3> MgCO3 > CaCO3 > SrCO3 >BaCO3 (Solubility)
  • BeCO3 < MgCO3 < CaCO3 < SrCO3 < BaCO3 (Thermal Stability)
  • BeSO4 < MgSO4 < CaSO4 < SrSO4 < BaSO4 (Thermal Stability)
  • BeSO4 > MgSO4 > CaSO4 > SrSO4 > BaSO4 (Solubility)
  • Be(NO3)2 < Mg(NO3)2 < Ca(NO3)2 < Sr(NO3)2 < Ba(NO3)2 (Solubility)
  • Be(NO3)2 < Mg(NO3)2 <Ca(NO3)2 < Sr(NO3)2 < Ba(NO3)2 (Thermal Stability)

→ Lime Water: Quick lime is a solid. It is mixed with water and called as lime water.

→ Important Points:

  • Na and K are stored in kerosene oil because it reacts with atmospheric vapour and form oxides.
  • Li is kept wrapped in paraffin wax because it floats on kerosene because of low density.
  • Among alkali metals carbonates, only lithium carbonate decomposes and gives carbon dioxide.
  • All alkali metals are strong reducing agents but lithium is strongest reducing agent among all.
  • Fire caught by alkali metals cannot be extinguished by water but can be extinguished by spraying CCl4.
  • All alkali metals and alkaline earth metals except Be and Mg gives flame test. .
  • The order of solubility of sulphates of alkaline earth metals in water is:
    BeSO4 > MgSO4 > CaSO4 > SrSO4 > BaSO4
  • The order of solubility of carbonates of alkaline earth metals in water is:
    BeCO3 > MgCO3 > CaCO3 > SrCO3 > BaCO3
  • Alkali metals dissolve in liquid ammonia and give blue conducting solution.
  • Lithium forms monoxide, sodium forms peroxide and others form superoxides.
  • Sodium carbonate is prepared by Solvay Method.
Prasanna
Last Updated on Oct. 22, 2022, 4:54 p.m.
Published Oct. 22, 2022