NCERT Class 11 Chemistry Hydrogen

Read and download NCERT Class 11 Chemistry Hydrogen chapter in NCERT book for Class 11 Chemistry. You can download latest NCERT eBooks for 2021 chapter wise in PDF format free from Studiestoday.com. 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

Hydrogen Class 11 Chemistry NCERT

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

Hydrogen NCERT Class 11

HYDROGEN

Hydrogen has the simplest atomic structure among all the elements around us in Nature. In atomic form it consists of only one proton and one electron. However, in elemental form it exists as a diatomic (H2) molecule and is called dihydrogen. It forms more compounds than any other element. Do you know that the global concern related to energy can be overcome to a great extent by the use of hydrogen as a source of energy? In fact, hydrogen is of great industrial importance as you will learn in this unit.

9.1 POSITION OF HYDROGEN IN THE PERIODIC TABLE

Hydrogen is the first element in the periodic table. However, its placement in the periodic table has been a subject of discussion in the past. As you know by now that the elements in the periodic table are arranged according to their electronic configurations.

Hydrogen has electronic configuration 1s1. On one hand, its electronic configuration is similar to the outer electronic configuration (ns1) of alkali metals , which belong to the first group of the periodic table. On the other hand, like halogens (with ns2np5 configuration belonging to the seventeenth group of the periodic table), it is short by one electron to the corresponding noble gas configuration, helium (1s2). Hydrogen, therefore, has resemblance to alkali metals, which lose one electron to form unipositive ions, as well as with halogens, which gain one electron to form uninegative ion. Like alkali metals, hydrogen forms oxides, halides and sulphides. However, unlike alkali metals, it has a very high ionization enthalpy and does not possess metallic characteristics under normal conditions. In fact, in terms of ionization enthalpy, hydrogen resembles more with halogens, Δi H of Li is 520 kJ mol–1, F is 1680 kJ mol–1 and that of H is 1312 kJ mol–1. Like halogens, it forms a diatomic molecule, combines with elements to form hydrides and a large number of covalent compounds. However, in terms of reactivity, it is very low as compared to halogens.

Inspite of the fact that hydrogen, to a certain extent resembles both with alkali metals and halogens, it differs from them as well. Now the pertinent question arises as where should it be placed in the periodic table? Loss of the electron from hydrogen atom results in nucleus (H+) of ~1.5×10–3 pm size. This is extremely small as compared to normal atomic and ionic sizes of 50 to 200pm. As a consequence, H+ does not exist freely and is always associated with other atoms or molecules. Thus, it is unique in behaviour and is, therefore, best placed separately in the periodic table (Unit 3).

9.2 DIHYDROGEN, H2

9.2.1 Occurrence

Dihydrogen is the most abundant element in the universe (70% of the total mass of the universe) and is the principal element in the solar atmosphere. The giant planets Jupiter and Saturn consist mostly of hydrogen.

However, due to its light nature, it is much less abundant (0.15% by mass) in the earth’s atmosphere. Of course, in the combined form it constitutes 15.4% of the earth's crust and the oceans. In the combined form besides in water, it occurs in plant and animal tissues, carbohydrates, proteins, hydrides including hydrocarbons and many other compounds.

9.2.2 Isotopes of Hydrogen

Hydrogen has three isotopes: protium, deuterium,  H or D and tritium, H or T. Can you guess how these isotopes differ from each other ? These isotopes differ from one another in respect of the presence of neutrons. Ordinary hydrogen, protium, has no neutrons, deuterium (also known as heavy hydrogen) has one and tritium has two neutrons in the nucleus. In the year 1934, an American scientist, Harold C. Urey, got Nobel Prize for separating hydrogen isotope of mass number 2 by physical methods. The predominant form is protium. Terrestrial hydrogen contains 0.0156% of deuterium mostly in the form of HD. The tritium concentration is about one atom per 1018 atoms of protium. Of these isotopes, only tritium is radioactive and emits low energy β– particles (t½, 12.33 years)


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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 Purification and Criteria of Purity
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
Part I Answer to Some Selected Problems
NCERT Class 11 Chemistry Answer of Some Selected Problems
Part I Appendices
NCERT Class 11 Chemistry Appendix 2 Elements Their Atomic Number and Molar Mass
NCERT Class 11 Chemistry Appendix 3
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
Part II Answer to Some Selected Problems
NCERT Class 11 Chemistry Answer to Some Selected Problems

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