Class 11 Chemistry - Chapter Hydrogen NCERT Solutions | Justify the position of hydrogen in the
Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.
Hydrogen is the first element of the periodic table & often called protium. Its electronic configuration is [1s1]. Due to the presence of only one electron in its 1s shell, hydrogen exhibits a dual behaviour, i.e., it resembles both alkali metals and halogens. As a result it is placed at the top of the alkali metals in group 1 & also along the halogens in group 17 since just like halogens,it also requires any one electron to have the configuration of the nearest noble gas element..The dual nature of hydrogen can be justified by following points:
Resemblance with alkali metals:
1. Like alkali metals, hydrogen contains one valence electron in its valence shell.
H : 1s1
Li : 1s2 2s1
Na : 1s2 2s2 2p6 3s1
Hence, it can lose one electron to form a unipositive ion.
2 Both hydrogen & alkali metals form monovalent cations by losing the electrons in the valence shell,showing hydrogens electropositive character similar to alkali metals.
H --------> H+ + e- , Na ---------->Na+ + e-
3 In their compounds both hydrogen & alkali metals show +1 oxidation states. Eg Hcl & Nacl
4 Both hydrogen & alkali metals are electropositive in nature,they have affinity for the electronegative elements & readily combine with them & form oxides, halides, and sulphides.
Resemblance with halogens:
1. Both hydrogen and halogens require one electron to complete their octets.
H : 1s1
F : 1s2 2s2 2p5
Cl : 1s2 2s2 2p6 3s2 3p5
Hence, hydrogen can gain one electron to form a uninegative ion.
2. Like halogens, it forms a diatomic molecule and several covalent compounds.
Though hydrogen shows some similarity with both alkali metals and halogens, it differs from them on some grounds. Unlike alkali metals, hydrogen does not possess metallic characteristics. On the other hand, it possesses a high ionization enthalpy. Also, it is less reactive than halogens.
Owing to these reasons, hydrogen cannot be placed with alkali metals (group I) or with halogens (group VII). In addition, it was also established that H+ ions cannot exist freely as they are extremely small. H+ ions are always associated with other atoms or molecules. Hence, hydrogen is best placed separately in the periodic table.
More Questions From Class 11 Chemistry - Chapter Hydrogen
- Q:-
Compare the structures of H2O and H2O2.
- Q:-
Write chemical reactions to show the amphoteric nature of water.
- Q:-
Arrange the following
(i) CaH2, BeH2 and TiH2 in order of increasing electrical conductance.
(ii) LiH, NaH and CsH in order of increasing ionic character.
(iii) H-H, D-D and F-F in order of increasing bond dissociation enthalpy.
(iv) NaH, MgH2 and H2O in order of increasing reducing property.
- Q:-
Discuss the principle and method of softening of hard water by synthetic ion-exchange resins.
- Q:-
What do you understand by the term “non-stoichiometric hydrides”? Do you expect this type of the hydrides to be formed by alkali metals? Justify your answer.
- Q:-
What is meant by 'demineralised' water and how can it be obtained?
- Q:-
What causes the temporary and permanent hardness of water?
- Q:-
How does H2O2 behave as a bleaching agent?
- Q:-
Why does hydrogen occur in a diatomic form rather than in a monoatomic form under normal conditions?
- Q:-
Describe the bulk preparation of dihydrogen by electrolytic method. What is the role of an electrolyte in this process?
Popular Questions of Class 11 Chemistry
- Q:-
How do you account for the formation of ethane during chlorination of methane?
- Q:-
What are hybridisation states of each carbon atom in the following compounds ?
(i) CH2=C=O,
(ii) CH3CH=CH2,
(iii) (CH3)2CO,
(iv) CH2=CHCN,
(v) C6H6
- Q:-
What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C?
- Q:-
What are the common physical and chemical features of alkali metals?
- Q:-
Calculate the molecular mass of the following:
(i) H2O
(ii) CO2
(iii) CH4 - Q:-
Assign oxidation number to the underlined elements in each of the following species:
(a) NaH2PO4
(b) NaHSO4
(c) H4P2O7
(d) K2MnO4
(e) CaO2
(f) NaBH4
(g) H2S2O7
(h) KAl(SO4)2.12 H2O
- Q:-
What is the basic theme of organisation in the periodic table?
- Q:-
Explain the formation of a chemical bond.
- Q:-
Choose the correct answer. A thermodynamic state function is a quantity
(i) used to determine heat changes
(ii) whose value is independent of path
(iii) used to determine pressure volume work
(iv) whose value depends on temperature only. - Q:-
A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.
a) What is the initial effect of the change on vapour pressure?
b) How do rates of evaporation and condensation change initially?
c) What happens when equilibrium is restored finally and what will be the final vapour pressure?
Recently Viewed Questions of Class 11 Chemistry
- Q:-
Fluorine reacts with ice and results in the change:
H2O(s) + F2(g) → HF(g) + HOF(g)
Justify that this reaction is a redox reaction.
- Q:-
Calculate the volume occupied by 8.8 g of CO2 at 31.1°C and 1 bar pressure.
R = 0.083 bar L K–1 mol–1.
- Q:-
Calculate the wavelength, frequency and wave number of a light wave whose period is 2.0 × 10–10 s.
- Q:-
An aqueous solution of borax is
(a) neutral (b) amphoteric (c) basic (d) acidic
- Q:-
If ten volumes of dihydrogen gas react with five volumes of dioxygen gas, how many volumes of water vapour would be produced?
- Q:-
For the reaction, 2Cl(g) → Cl2(g),what are the signs of ΔH and ΔS ?
- Q:-
Which one of the following will have largest number of atoms?
(i) 1 g Au (s)
(ii) 1 g Na (s)
(iii) 1 g Li (s)
(iv) 1 g of Cl2(g)
- Q:-
0.3780 g of an organic chloro compound gave 0.5740 g of silver chloride in Carius estimation. Calculate the percentage of chlorine present in the compound.
- Q:-
Ionic product of water at 310 K is 2.7 x 10-14. What is the pH of neutral water at this temperature?
- Q:-
If the density of methanol is 0.793 kg L–1, what is its volume needed for making 2.5 L of its 0.25 M solution?
10 Comment(s) on this Question
It's very useful
It's educating
well explained
Hey hey
Thank u
It is very good
why u don\'t given all questions answer...ð¬
why u don't given all questions answer...ð¬
nice iits really helpful
It was so very helpful Thank u so mch ð
- All Chapters Of Class 11 Chemistry
- All Subjects Of Class 11