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Discuss the general characteristics and gradation in properties of alk...

Discuss the general characteristics and | Class 11 Chemistry Chapter The s Block Elements, The s Block Elements NCERT Solutions

Welcome to the NCERT Solutions for Class 11 Chemistry - Chapter The s Block Elements. This page offers a step-by-step solution to the specific question from Exercise 1, Question 2: . With detailed answers and explanations for each chapter, students can strengthen their understanding and prepare confidently for exams. Ideal for CBSE and other board students, this resource will simplify your study experience.

Question 2:

Discuss the general characteristics and gradation in properties of alkaline earth metals.

Answer:

General characteristics of alkaline earth metals are as follows.

(i) The general electronic configuration of alkaline earth metals is [noble gas] ns².

(ii)These metals lose two electrons to acquire the nearest noble gas configuration. Therefore, their oxidation state is +2.

(iii)These metals have atomic and ionic radii smaller than that of alkali metals. Also, when moved down the group, the effective nuclear charge decreases and this causes an increase in their atomic radii and ionic radii.

(iv) Since the alkaline earth metals have large size, their ionization enthalpies are found to be fairly low. However, their first ionization enthalpies are higher than the corresponding group 1 metals.

(v) These metals are lustrous and silvery white in appearance. They are relatively less soft as compared to alkali metals.

(vi) Atoms of alkaline earth metals are smaller than that of alkali metals. Also, they have two valence electrons forming stronger metallic bonds. These two factors cause alkaline earth metals to have high melting and boiling points as compared to alkali metals.

(vii) They are highly electropositive in nature. This is due to their low ionization enthalpies. Also, the electropositive character increases on moving down the group from Be to Ba.

(viii) Ca, Sr, and Ba impart characteristic colours to flames.

Ca - Brick red

Sr - Crimson red

Ba - Apple green

In Be and Mg, the electrons are too strongly bound to be excited. Hence, these do not impart any colour to the flame.

The alkaline earth metals are less reactive than alkali metals and their reactivity increases on moving down the group. Chemical properties of alkaline earth metals are as follows.

(i) Reaction with air and water: Be and Mg are almost inert to air and water because of the formation of oxide layer on their surface.

(a) Powdered Be burns in air to form BeO and Be₃N₂.

(b) Mg, being more electropositive, burns in air with a dazzling sparkle to form MgO and Mg₃N₂.

(d) Ca, Ba, and Sr react vigorously even with cold water.

(ii) Alkaline earth metals react with halogens at high temperatures to form halides.

M + X₂ → MX₂ (X = F,Cl,Br,I)

(iii) All the alkaline earth metals, except Be, react with hydrogen to form hydrides.

(iv) They react readily with acids to form salts and liberate hydrogen gas.

M + 2HCl → MCl₂ + H_2(g) ↑

(v) They are strong reducing agents. However, their reducing power is less than that of alkali metals. As we move down the group, the reducing power increases.

(vi) Similar to alkali metals, the alkaline earth metals also dissolve in liquid ammonia to give deep blue coloured solutions.

M + (x-y)NH₃ → [M(NH₃)_x]⁺² + 2[e(NH₃)_y]^-

Other Questions of Chapter The s Block Elements

Describe the importance of the following: (i) limestone (ii) cement (iii) plaster of paris.

Explain the significance of sodium, potassium, magnesium and calcium inbiological fluids.

In what ways lithium shows similarities to magnesium in its chemical behaviour?

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

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

What happens when

(i) sodium metal is dropped in water ?

(ii) sodium metal is heated in free supply of air ?

(iii) sodium peroxide dissolves in water ?

Comment on each of the following observations:

(a) The mobilities of the alkali metal ions in aqueous solution are Li⁺ < Na⁺ < K⁺ < Rb⁺ < Cs⁺

(b) Lithium is the only alkali metal to form a nitride directly.

Why are lithium salts commonly hydrated and those of the other alkali metal ions usually anhydrous?

What happens when

(i) magnesium is burnt in air

(ii) quick lime is heated with silica

(iii) chlorine reacts with slaked lime

(iv) calcium nitrate is heated ?

When an alkali metal dissolves in liquid ammonia the solution can acquire different colours. Explain the reasons for this type of colour change.

Popular questions of class 11 Chemistry

Calculate the amount of carbon dioxide that could be produced when

(i) 1 mole of carbon is burnt in air.

(ii) 1 mole of carbon is burnt in 16 g of dioxygen.

(iii) 2 moles of carbon are burnt in 16 g of dioxygen.

The mass of an electron is 9.1 × 10^–31 kg. If its K.E. is 3.0 × 10^–25 J, calculate its wavelength.

Calculate the wavelength of an electron moving with a velocity of 2.05 × 10⁷ ms^–1.

Balance the following redox reactions by ion – electron method :

(a) MnO₄^–(aq) + I^–(aq) → MnO_{2 (s)} + I_2(s) (in basic medium)

(b) MnO₄ ^– (aq) + SO_{2 (g)}→ Mn²⁺ (aq) + HSO₄^– (aq) (in acidic solution)

(d) Cr₂O₇ ^2– + SO_2(g) → Cr³⁺ _(aq) + SO₄^2–(aq) (in acidic solution)

In a process, 701 J of heat is absorbed by a system and 394 J ofwork is done by the system. What is the change in internal energy for the process?

What will be the minimum pressure required to compress 500 dm³ of air at 1 bar to 200 dm³ at 30°C?

In a reaction A + B2 → AB2 Identify the limiting reagent, if any, in the following reaction mixtures.

(i) 300 atoms of A + 200 molecules of B

(ii) 2 mol A + 3 mol B

(iii) 100 atoms of A + 100 molecules of B

(iv) 5 mol A + 2.5 mol B

(v) 2.5 mol A + 5 mol B

At 0°C, the density of a certain oxide of a gas at 2 bar is same as that of dinitrogen at 5 bar. What is the molecular mass of the oxide?

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)

Density of a gas is found to be 5.46 g/dm³ at 27 °C at 2 bar pressure. What will be its density at STP?

Recently Viewed Questions of Class 11 Chemistry

How would you convert the following compounds into benzene?

(i) Ethyne (ii) Ethene (iii) Hexane

Explain structures of diborane and boric acid.

For the following equilibrium, K_c= 6.3 × 10¹⁴ at 1000 K

NO (g) + O₃ (g) ↔ NO₂ (g) + O₂(g)

Both the forward and reverse reactions in the equilibrium are elementary bimolecular reactions. What is K_c, for the reverse reaction?

Describe the change in hybridisation (if any) of the Al atom in the following reaction.

Find out the value of K_c for each of the following equilibria from the value of K_p:

(i) 2NOCl (g) ↔ 2NO (g) + Cl₂ (g); Kp = 1.8 × 10^–2 at 500 K

(ii) CaCO₃ (s) ↔ CaO(s) + CO₂(g); Kp = 167 at 1073 K

In a reaction A + B2 → AB2 Identify the limiting reagent, if any, in the following reaction mixtures.

(i) 300 atoms of A + 200 molecules of B

(ii) 2 mol A + 3 mol B

(iii) 100 atoms of A + 100 molecules of B

(iv) 5 mol A + 2.5 mol B

(v) 2.5 mol A + 5 mol B

Find energy of each of the photons which

(i) correspond to light of frequency 3× 1015 Hz.

(ii) have wavelength of 0.50 Å.

Calculate the number of kJ of heat necessary to raise the temperature of 60.0 g of aluminium from 35°C to 55°C. Molar heat capacity of Al is 24 J mol^–1 K^–1.

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?

Write Lewis symbols for the following atoms and ions:

S and S2–; Al and Al3+; H and H–

Study Tips for Answering NCERT Questions:

NCERT questions are designed to test your understanding of the concepts and theories discussed in the chapter. Here are some tips to help you answer NCERT questions effectively:

Read the question carefully and focus on the core concept being asked.
Reference examples and data from the chapter when answering questions about The s Block Elements.
Review previous year question papers to get an idea of how such questions may be framed in exams.
Practice answering questions within the time limit to improve your speed and accuracy.
Discuss your answers with your teachers or peers to get feedback and improve your understanding.

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