NCERT Class 11 Chemistry The s Block Elements

Read and download NCERT Class 11 Chemistry The s Block Elements chapter in NCERT book for Class 11 Chemistry. You can download latest NCERT eBooks for 2021 chapter wise in PDF format free from This Chemistry textbook for Class 11 is designed by NCERT and is very useful for students. Please also refer to the NCERT solutions for Class 11 Chemistry to understand the answers of the exercise questions given at the end of this chapter

The S Block Elements Class 11 Chemistry NCERT

Class 11 Chemistry students should refer to the following NCERT Book chapter The S Block Elements in standard 11. This NCERT Book for Grade 11 Chemistry will be very useful for exams and help you to score good marks

The S Block Elements NCERT Class 11


The s-block elements of the Periodic Table are those in which the last electron enters the outermost s-orbital. As the s-orbital can accommodate only two electrons, two groups (1 & 2) belong to the s-block of the Periodic Table.Group 1 of the Periodic Table consists of the elements: lithium, sodium, potassium, rubidium, caesium and francium. They are collectively known as the alkali metals. These are so called because they form hydroxides on reaction with water which are strongly alkaline in nature. The elements of Group 2 include beryllium, magnesium, calcium, strontium, barium and radium. These elements with the exception of beryllium are commonly known as the alkaline earth metals. These are so called because their oxides and hydroxides are alkaline in nature and these metal oxides are found in the earth’s crust.

Among the alkali metals sodium and potassium are abundant and lithium, rubidium and caesium have much lower abundances (Table 10.1). Francium is highly radioactive; its longest-lived isotope 223Fr has a half-life of only 21 minutes. Of the alkaline earth metals calcium and magnesium rank fifth and sixth in abundance respectively in the earth’s crust. Strontium and barium have much lower abundances. Beryllium is rare and radium is the rarest of all comprising only 10–10 per cent of igneous rocks† (Table 10.2, page 299).

The general electronic configuration of s-block elements is [noble gas]ns1 for alkali metals and [noble gas] ns2 for alkaline earth metals. 

Lithium and beryllium, the first elements of Group 1 and Group 2 respectively exhibit some properties which are different from those of the other members of the respective group. In these anomalous properties they resemble the second element of the following group. Thus, lithium shows similarities to magnesium and beryllium to aluminium in many of their properties.

This type of diagonal similarity is commonly referred to as diagonal relationship in the periodic table. The diagonal relationship is due to the similarity in ionic sizes and /or charge/radius ratio of the elements. Monovalent sodium and potassium ions and divalent magnesium and calcium ions are found in large proportions in biological fluids. These ions perform important biological functions such as maintenance of ion balance and nerve impulse conduction.


The alkali metals show regular trends in their physical and chemical properties with the increasing atomic number. The atomic, physical and chemical properties of alkali metals are discussed below.

10.1.1 Electronic Configuration

All the alkali metals have one valence electron, ns1 (Table 10.1) outside the noble gas core. The loosely held s-electron in the outermost valence shell of these elements makes them the most electropositive metals. They readily lose electron to give monovalent M+ ions. Hence they are never found in free state in nature.

10.1.2 Atomic and Ionic Radii

The alkali metal atoms have the largest sizes in a particular period of the periodic table. With increase in atomic number, the atom becomes larger. The monovalent ions (M+) are smaller than the parent atom. The atomic and ionic radii of alkali metals increase on moving down the group i.e., they increase in size while going from Li to Cs.

10.1.3 Ionization Enthalpy

The ionization enthalpies of the alkali metals are considerably low and decrease down the group from Li to Cs. This is because the effect of increasing size outweighs the increasing nuclear charge, and the outermost electron is very well screened from the nuclear charge.

10.1.4 Hydration Enthalpy

The hydration enthalpies of alkali metal ions decrease with increase in ionic sizes. 

Li+> Na+ > K+ > Rb+ > Cs+ Li+

has maximum degree of hydration and for this reason lithium salts are mostly hydrated, e.g., LiCl· 2H2O

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Chapter 1 Some Basic Concepts of Chemistry
NCERT Class 11 Chemistry Some Basic Concepts Of Chemistry
Chapter 2 Structure of Atom
NCERT Class 11 Chemistry Structure of Atom
Chapter 3 Classification of Elements and Periodicity in Properties
NCERT Class 11 Chemistry Classification of Elements and Periodicity In Properties
Chapter 4 Chemical Bonding and Molecular Structure
NCERT Class 11 Chemistry Chemical Bonding and Molecular Structure
Chapter 5 States of Matter
NCERT Class 11 Chemistry State Of Matter
Chapter 6 Thermodynamics
NCERT Class 11 Chemistry Thermodynamics
Chapter 7 Equilibrium
NCERT Class 11 Chemistry Equilibrium
Chapter 8 Redox Reactions
NCERT Class 11 Chemistry Redox Reactions
Chapter 9 Hydrogen
NCERT Class 11 Chemistry Hydrogen
Chapter 10 The s-Block Elements
NCERT Class 11 Chemistry The s Block Elements
Chapter 11 The p-Block Elements
NCERT Class 11 Chemistry The p Block Elements
Chapter 12 Organic Chemistry – Some Basic Principles & Techniques
NCERT Class 11 Chemistry Organic Chemistry Some Basic Priciples and Techniques
Chapter 13 Hydrocarbons
NCERT Class 11 Chemistry Hydrocarbons
Chapter 14 Environmental Chemistry
NCERT Class 11 Chemistry Environmental Chemistry
Other Chapters
NCERT Class 11 Chemistry Lab Manual Systematics Qualitative Analysis
NCERT Class 11 Chemistry Lab Manual Basic Laboratory Techniques
NCERT Class 11 Chemistry Lab Manual Titrimetric Analysis
NCERT Class 11 Chemistry Lab Manual Chemical Equilibrium Ionic Equilibrium
NCERT Class 11 Chemistry Lab Manual Information about Investigatory Projects
NCERT Class 11 Chemistry Lab Manual Introduction
NCERT Class 11 Chemistry Lab Manual ph and ph change in Aqueous Solutions
NCERT Class 11 Chemistry Lab Manual Purification and Criteria of Purity
Part I Answer to Some Selected Problems
NCERT Class 11 Chemistry Answer of Some Selected Problems
Part I Appendices
NCERT Class 11 Chemistry Appendix 4 Physical Constants
NCERT Class 11 Chemistry Appendix 5 Some Useful Conversion Factores
NCERT Class 11 Chemistry Appendix 6 Thernodynamic Data at 298 K
NCERT Class 11 Chemistry Appendix 7 Standard Potentials at 298 K in Electrochemical order
NCERT Class 11 Chemistry Appendix 1
NCERT Class 11 Chemistry Appendix 2 Elements Their Atomic Number and Molar Mass
NCERT Class 11 Chemistry Appendix 3
Part II Answer to Some Selected Problems
NCERT Class 11 Chemistry Answer to Some Selected Problems

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