12. s-Block Elements - JEE Main - Core Points for Revision

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

Core Revision Points in Sections in Jauhar's Book

12.1 Abundance and Occurrence
12.2 Anomalous Properties of First Element in Each Group
12.3 Diagonal Relationship

Chemistry of Alkali Metals

12.4 Occurrence
12.5 General Characteristics of Alkali Metals
Alkali metals are soft having low melting and boiling points. This is due to weak intermetallic bonding.


12.6 General Characteristics of Compounds of Alkali Metals
12.7 Anomalous Behavior of Lithium
12.8 Diagonal Relationship

Chemistry of Li and Na and Its Compounds

12.9 Occurrence of Lithium and Sodium

Sodium metal is kept under kerosene because it is very reactive and if exposed to air,  it reacts with oxygen and carbon dioxide.
12.10 Extraction of Lithium and Sodium
12.11 Some Important Compounds of Sodium

LiCl is covalent in nature due high polarising power of Li+. Being covalent in nature, it is soluble in organic solvent.

LiH is more stable than NaH as LiH has more lattice energy.

Chemistry of Alkaline Earth Metals

12.12 Occurrence
12.13 General Characteristics of Alkaline Earth Metals
12.14 General Characteristics of Compounds of Alkaline Earth Metals
12.15 Differences between Beryllium and Magnesium
12.16 Diagonal Similarities of Beryllium and Aluminium

12.17 Occurrence of Magnesium
Magnesium - Chemistry

12.18 Compounds of Magnesium and Calcium

Compounds of Magnesium

Compounds of  Calcium

CaO is quick lime. On adding water to it, calcium hydroxide is formed. This process is called slaking of lime.

Plaster of paris is CaSo4.1/2 H2O. On mixing with water, it forms a plastic mass which sets inot hard solid mass (gypsum). This change is called setting of plaster of paris.


12.19 Industrial Uses of Limestone and Lime


12.20 Cement
Cement is called portland cement because it resembles with the famous building stone found near Portland in England.

Cement was first introduced in England in 1824 by Joseph Aspidin.

Chemically, cement is a finely ground mixture of calcium silicates and aluminates which set to a hard mass when treated with water.



Practice problems

http://makoxmcqs.com/chemistry-mcqs-for-iit-jee-s-block-elements-mcq-practice-sheet/




Sections in Jauhar's Book

12.1 Abundance and Occurrence
12.2 Anomalous Properties of First Element in Each Group
12.3 Diagonal Relationship

Chemistry of Alkali Metals

12.4 Occurrence
12.5 General Characteristics of Alkali Metals
12.6 General Characteristics of Compounds of Alkali Metals
12.7 Anomalous Behavior of Lithium
12.8 Diagonal Relationship

Chemistry of Li and Na and Its Compounds

12.9 Occurrence of Lithium and Sodium

12.10 Extraction of Lithium and Sodium

12.11 Some Important Compounds of Sodium

Chemistry of Alkaline Earth Metals

12.12 Occurrence
12.13 General Characteristics of Alkaline Earth Metals
12.14 General Characteristics of Compounds of Alkaline Earth Metals
12.15 Differences between Beryllium and Magnesium
12.16 Diagonal Similarities of Beryllium and Aluminium


12.17 Occurrence of Magnesium


12.18 Compounds of Magnesium and Calcium

Compounds of Magnesium

Compounds of  Calcium
12.19 Industrial Uses of Limestone and Lime
12.20 Cement



Updated on 2 January 2020
21 May 2019

Magnesium - Chemistry

Magnesium occupies sixth position in order of the abundance on earth.

Magnesium is greyish white metal.

Magnesium is the lightest metal used in industry and it has a density less than two thirds of aluminium. Magnesium is an important alloying metal.

Uses:

Some of the alloys of magnesium containing more than 90% magnesium and 2 to 9% of Aluminium and 1% zinc are used in automobile engines, in aircrafts and in making balances.
Up to 5% magnesium is added to most commercial aluminium alloys (duralumin, magnalium) to improve its resistance to corrosion, mechanical properties and weldability.

Magnesium is used as a reducing agent in metallurgy for the production of metals such as Titanium (Ti), Zirconium (Zr) and Hf.

Magnesium power is used in fireworks.

It is part of alkyl magnesium halide (RMgX), the Grignard reagent and it is useful for making number of organic compounds.

Magnesium hydroxide and magnesium carbonate are used in making toothpastes.

Magnesium hydroxide (milk of magnesia) is used as an antacid. It neutralises excess of acid in stomach and thus it is used as medicine.

Ores of Magnesium

1. Carnallite
2. Magnesite
3. Dolomite
4. Epsom salt or epsomite
5. Langbeinite
6. Asbestos

Extraction of Magnesium from Its Ores

Magnesium is finally extracted by the electrolysis of its molten anhydrous salts.

From Magnesite
The ore MgCO3 is calcined to form the oxide MgO.
The oxide is mixed with carbon and heated in a current of Cl2 gas to form magnesium chloride.
Magnesium chloride is subjected to electrolysis.

Electrolysis of Magnesium chloride

Magnesium chloride is with a mixture of sodium chloride and calcium chloride and heated to 973 K - 1023 K. The mixture melts at this temperature and the electrolysis in carried out in an iron vessel which serves as the cathode.  A graphite rod serves as anode. During the electrolysis an inert gas such as coal gas is passed through the cell to check the oxidation of magnesium. At cathode magnesium will emerge in molten state and at anode chlorine gas will be released. The liquid magnesium (m.p. 924K) is removed from time to time from the top of the vessel.

Magnesium is a s-Block element.

IIT JEE Chemistry - Study Guide - Study Plan - 12. s-Block Elements

Sections in Jauhar's Book

12.1 Abundance and Occurrence
12.2 Anomalous Properties of First Element in Each Group
12.3 Diagonal Relationship

Chemistry of Alkali Metals

12.4 Occurrence
12.5 General Characteristics of Alkali Metals
12.6 General Characteristics of Compounds of Alkali Metals
12.7 Anomalous Behavior of Lithium
12.8 Diagonal Relationship

Chemistry of Li and Na and Its Compounds

12.9 Occurrence of Lithium and Sodium
12.10 Extraction of Lithium and Sodium
12.11 Some Important Compounds of Sodium

Chemistry of Alkaline Earth Metals

12.12 Occurrence
12.13 General Characteristics of Alkaline Earth Metals
12.14 General Characteristics of Compounds of Alkaline Earth Metals
12.15 Differences between Beryllium and Magnesium
12.16 Diagonal Similarities of Beryllium and Aluminium
12.17 Occurrence of Magnesium
12.18 Compounds of Magnesium and Calcium
12.19 Industrial Uses of Limestone and Lime
12.20 Cement

Conceptual Questions with Answers: 14
Additional Numerical Problems for Practice:
Revision Exercises
Very Short Answer questions: 30
Short Answer Questions : 55
Long Answer Questions 15

Competition File
Numerical Problems
Objective Questions: 25
Fill in the blanks: 10
True or False: 10

Study Plan


Day 1

12.1 Abundance and Occurrence
12.2 Anomalous Properties of First Element in Each Group
12.3 Diagonal Relationship

Chemistry of Alkali Metals

12.4 Occurrence
12.5 General Characteristics of Alkali Metals

Day
12.5 contd. Chemical Properties

Day 3
12.6 General Characteristics of Compounds of Alkali Metals
12.7 Anomalous Behavior of Lithium
12.8 Diagonal Relationship

day 4

Chemistry of Li and Na and Its Compounds

12.9 Occurrence of Lithium and Sodium
12.10 Extraction of Lithium and Sodium

Day 5
12.11 Some Important Compounds of Sodium
Practice Problems
12.1 to 12.10


Day 6
Chemistry of Alkaline Earth Metals

12.12 Occurrence
12.13 General Characteristics of Alkaline Earth Metals
12.14 General Characteristics of Compounds of Alkaline Earth Metals
12.15 Differences between Beryllium and Magnesium

day 7
12.16 Diagonal Similarities of Beryllium and Aluminium
PP. 12.11 to 12.14
12.17 Occurrence of Magnesium
12.18 Compounds of Magnesium and Calcium

Day 8
PP. 12.15 to 12.24
12.19 Industrial Uses of Limestone and Lime
12.20 Cement

Conceptual Questions with Answers: 14
Day 9


Revision Exercises: Very Short Answer questions: 30
Revision Exercises: Short Answer questions: 1to 30

Day 10
Revision Exercises: Short Answer questions: 31 to 55

Revision Period

Day 11
Competition File - Objective Questions: 25

Day 12
Competition File - Fill in the blanks: 10
Competition File - True or False: 10

Day 13 to Day 20
Revision