Class 11 Chemistry The S Block Elements Biological importance of s-block elements

 Biological importance of s-block elements

  • Sodium ions are found in the blood plasma and in the interstitial fluid surroundingthe cells.
  • They stimulate the nerve signals and also regulate the flow of water across cell membranes. It also transports the sugars and amino acids into cells.

  • A potassium ion activates many enzymes within the cell fluids and also oxidizes glucose to produce ATP.
  • Enzymes utilizing ATP requires magnesium as co-factor.
  • The pigment responsible for absorption of light by the leaves during photosynthesis is chlorophyll which contains magnesium.
  • In human body calcium is present in bones and teeth.


  • It plays a crucial role in neuromuscular function,interneuronal transmission, cell membraneintegrity and blood coagulation.
  • The calciumconcentration in plasma is maintained by the hormones namely, calcitonin and parathyroid.

Question. Draw the structure of (i) BeCl2 (vapour) (ii) BeCl2 (solid).


Question: Why is LiF almost insoluble in water whereas LiCl soluble not only in water but also in acetone?

Answer: Smaller size of fluoride ion due to which LiF has greater lattice energy than LiCI. Net change in energy during the dissolution of LiCI in water is more exothermic than dissolution of LiF in water. Solubility of LiCl in water and acetone is due to its low lattice energy and greater covalent character.


Question: Write balanced equations for reactions between
(a) Na2O2 and water
(b) KO2 and water
(c) Na2O and CO2


(a) 2 Na2O2(s) + 2 H2O(l) --> 4 NaOH(aq) + O2(g)

(b) 20 KO2 + H20 --> 20 KOH + 10 O2

(c) 2 Na2O + 3 Co2 --> 2 Na2Co3 + O2


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