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NCERT solutions Chemistry Class 11 Part 1 chapter 3 Classification of Elements and Periodicity in Properties

Chapters

NCERT Solutions for Chemistry Class 11 Part 2

NCERT Chemistry Class 11 Part 1

Chemistry Textbook for Class 11 Part 1

Chapter 3 - Classification of Elements and Periodicity in Properties

Pages 92 - 95

What is the basic theme of the organisation in the periodic table?

Q 1 | Page 92

Which important property did Mendeleev use to classify the elements in his periodic table and did he stick to that?

Q 2 | Page 92

What is the basic difference in approach between the Mendeleev’s Periodic Law and the Modern Periodic Law?

Q 3 | Page 92

On the basis of quantum numbers, justify that the sixth period of the periodic table should have 32 elements.

Q 4 | Page 92

In terms of period and group, where would you locate the element with =114?

Q 5.1 | Page 93

Write the atomic number of the element present in the third period and a seventeenth group of the periodic table.

Q 5.2 | Page 93

Which element do you think would have been named by Lawrence Berkeley Laboratory?

Q 7.1 | Page 93

Which element do you think would have been named by Seaborg’s group?

Q 7.2 | Page 93

Why do elements in the same group have similar physical and chemical properties?

Q 8 | Page 93

What does atomic radius and ionic radius really mean to you?

Q 9 | Page 93

How does atomic radius vary in a period and in a group? How do you explain the variation?

Q 10 | Page 93

What do you understand by isoelectronic species? Name a species that will be isoelectronic with the following atom or ion:-

F

Q 11.1 | Page 93

What do you understand by isoelectronic species? Name a species that will be isoelectronic with the following atom or ion:-

Ar

Q 11.2 | Page 93

What do you understand by isoelectronic species? Name a species that will be isoelectronic with the following atom or ion:-

Mg2+

Q 11.3 | Page 93

What do you understand by isoelectronic species? Name a species that will be isoelectronic with the following atom or ion:-

Rb+

Q 11.4 | Page 93

Consider the following species:-

N3–, O2–, F, Na+, Mg2+ and Al3+

Arrange them in the order of increasing ionic radii.

Q 12.1 | Page 93

Consider the following species:-

N3–, O2–, F, Na+, Mg2+ and Al3+

What is common in them?

Q 12.2 | Page 93

Explain why cations are smaller and anions larger in radii than their parent atoms?

Q 13 | Page 93

What is the significance of the terms - ‘isolated gaseous atom’ and ‘ground state’ while defining the ionization enthalpy and electron gain enthalpy?

Hint: Requirements for comparison purposes.

Q 14 | Page 93

Energy of an electron in the ground state of the hydrogen atom is –2.18 × 10–18 J. Calculate the ionization enthalpy of atomic hydrogen in terms of J mol–1.

Q 15 | Page 93

Among the second period elements the actual ionization enthalpies are in the

order Li < B < Be < C < O < N < F < Ne.

Explain why Be has higher Δithan B?

Q 16 | Page 93

Among the second period elements the actual ionization enthalpies are in the

order Li < B < Be < C < O < N < F < Ne.

Explain why O has lower Δithan N and F?

Q 16 | Page 93

How would you explain the fact that the first ionization enthalpy of sodium is lower than that of magnesium but its second ionization enthalpy is higher than that of magnesium?

Q 17 | Page 93

What are the various factors due to which the ionization enthalpy of the main group elements tends to decrease down a group?

Q 18 | Page 93

The first ionization enthalpy values (in kJmol–1) of group 13 elements are:-

B Al Ga In Tl
801 577 579 558 589

How would you explain this deviation from the general trend?

Q 19 | Page 93

Which of the following pairs of elements would have a more negative electron gain enthalpy?

(i) O or F (ii) F or Cl

Q 20 | Page 93

Would you expect the second electron gain enthalpy of O as positive, more negative or less negative than the first? Justify your answer.

Q 21 | Page 93

What is the basic difference between the terms electron gain enthalpy and electronegativity?

Q 22 | Page 93

How would you react to the statement that the electronegativity of N on Pauling scale is 3.0 in all the nitrogen compounds?

Q 23 | Page 93

Describe the theory associated with the radius of an atom as it gains an electron.

Q 24.1 | Page 94

Describe the theory associated with the radius of an atom as it loses an electron.

Q 24.2 | Page 94

Would you expect the first ionization enthalpies for two isotopes of the same element to be the same or different? Justify your answer.

Q 25 | Page 94

What are the major differences between metals and non-metals?

Q 26 | Page 94

Use the periodic table to answer the following question

Identify an element with five electrons in the outer subshell.

Q 27.1 | Page 94

Use the periodic table to answer the following question

Identify an element that would tend to lose two electrons.

Q 27.2 | Page 94

Use the periodic table to answer the following question

Identify an element that would tend to gain two electrons.

Q 27.3 | Page 94

Use the periodic table to answer the following question

Identify the group having metal, non-metal, liquid as well as gas at the room temperature.

Q 27.4 | Page 94

The increasing order of reactivity among group 1 elements is Li < Na < K < Rb CI > Br > I. Explain.

Q 28 | Page 94

Write the general outer electronic configuration of f- block elements.

Q 29.1 | Page 94

Write the general outer electronic configuration of d- block elements.

Q 29.2 | Page 94

Write the general outer electronic configuration of s- block elements.

Q 29.3 | Page 94

Write the general outer electronic configuration of p- block elements.

Q 29.4 | Page 94

Assign the position of the element having an outer electronic configuration in the periodic table.

ns2 np4 for = 3

Q 30.1 | Page 94

Assign the position of the element having an outer electronic configuration in the periodic table.

(- 1)d2 ns2 for = 4

Q 30.2 | Page 94

Assign the position of the element having an outer electronic configuration in the periodic table.

f7 (n - 1)d1 ns2 for n = 6

Q 30.2 | Page 94

The first (Δ1H1) and the second (Δ1H2) ionization enthalpies (in kJ mol-1) and the (ΔegH) electron gain enthalpy (in kJ mol-1) of a few elements are given below:

Elements Δ1H1 Δ1H2 ΔegH
I 520 7300 -60
II 419 3051 -48
III 1681 3374 -328
IV 1008 1846 -295
V 2372 5251 +48
VI 738 1451 -40

Which of the above elements is likely to be the least reactive element.

Q 31.1 | Page 94

The first (Δ1H1) and the second (Δ1H2) ionization enthalpies (in kJ mol-1) and the (ΔegH) electron gain enthalpy (in kJ mol-1) of a few elements are given below:

Elements Δ1H1 Δ1H2 ΔegH
I 520 7300 -60
II 419 3051 -48
III 1681 3374 -328
IV 1008 1846 -295
V 2372 5251 +48
VI 738 1451 -40

Which of the above elements is likely to be the most reactive metal.

Q 31.2 | Page 94

The first (Δ1H1) and the second (Δ1H2) ionization enthalpies (in kJ mol-1) and the (ΔegH) electron gain enthalpy (in kJ mol-1) of a few elements are given below:

Elements Δ1H1 Δ1H2 ΔegH
I 520 7300 -60
II 419 3051 -48
III 1681 3374 -328
IV 1008 1846 -295
V 2372 5251 +48
VI 738 1451 -40

Which of the above elements is likely to be the most reactive non-metal.

Q 31.3 | Page 94

The first (Δ1H1) and the second (Δ1H2) ionization enthalpies (in kJ mol-1) and the (ΔegH) electron gain enthalpy (in kJ mol-1) of a few elements are given below:

Elements Δ1H1 Δ1H2 ΔegH
I 520 7300 -60
II 419 3051 -48
III 1681 3374 -328
IV 1008 1846 -295
V 2372 5251 +48
VI 738 1451 -40

Which of the above elements is likely to be the least reactive non-metal.

Q 31.4 | Page 94

The first (Δ1H1) and the second (Δ1H2) ionization enthalpies (in kJ mol-1) and the (ΔegH) electron gain enthalpy (in kJ mol-1) of a few elements are given below:

Elements Δ1H1 Δ1H2 ΔegH
I 520 7300 -60
II 419 3051 -48
III 1681 3374 -328
IV 1008 1846 -295
V 2372 5251 +48
VI 738 1451 -40

Which of the above elements is likely to be the metal which can form a stable binary halide of the formula MX2, (X=halogen).

Q 31.5 | Page 94

The first (Δ1H1) and the second (Δ1H2) ionization enthalpies (in kJ mol-1) and the (ΔegH) electron gain enthalpy (in kJ mol-1) of a few elements are given below:

Elements Δ1H1 Δ1H2 ΔegH
I 520 7300 -60
II 419 3051 -48
III 1681 3374 -328
IV 1008 1846 -295
V 2372 5251 +48
VI 738 1451 -40

Which of the above elements is likely to be the metal which can form a predominantly stable covalent halide of the formula MX (X=halogen)?

Q 31.5 | Page 94

Predict the formula of the stable binary compounds that would be formed by the combination of the following pair of elements.

Lithium and oxygen

Q 32.1 | Page 94

Predict the formula of the stable binary compounds that would be formed by the combination of the following pair of elements.

Magnesium and nitrogen

Q 32.2 | Page 94

Predict the formula of the stable binary compounds that would be formed by the combination of the following pair of elements.

Aluminium and iodine

Q 32.3 | Page 94

Predict the formula of the stable binary compounds that would be formed by the combination of the following pair of elements.

Silicon and oxygen

Q 32.4 | Page 94

Predict the formula of the stable binary compounds that would be formed by the combination of the following pair of elements.

Element 71 and fluorine

Q 32.5 | Page 94

Predict the formula of the stable binary compounds that would be formed by the combination of the following pair of elements.

Phosphorus and fluorine

Q 32.6 | Page 94

In the modern periodic table, the period indicates the value of:-

(a) Atomic number

(b) Atomic mass

(c) Principal quantum number

(d) Azimuthal quantum number.

Q 33.1 | Page 94

Which of the following statements related to the modern periodic table is incorrect?

(a) The p-block has 6 columns, because a maximum of 6 electrons can occupy all the orbitals in a p-shell.

(b) The d-block has 8 columns because a maximum of 8 electrons can occupy all the orbitals in a d-subshell.

(c) Each block contains a number of columns equal to the number of electrons that can occupy that subshell.

(d) The block indicates the value of azimuthal quantum number () for the last subshell that received electrons in building up the electronic configuration.

Q 33.2 | Page 94

Anything that influences the valence electrons will affect the chemistry of the element. Which one of the following factors does not affect the valence shell?

(a) Valence principal quantum number (n)

(b) Nuclear charge (Z)

(c) Nuclear mass

(d) Number of core electrons.

Q 35 | Page 95

The size of isoelectronic species — F, Ne and Na+ is affected by

(a) Nuclear charge ()

(b) Valence principal quantum number (n)

(c) Electron-electron interaction in the outer orbitals

(d) None of the factors because their size is the same.

Q 36 | Page 95

Which one of the following statements is incorrect in relation to ionization enthalpy?

(a) Ionization enthalpy increases for each successive electron.

(b) The greatest increase in ionization enthalpy is experienced on removal of electron from core noble gas configuration.

(c) End of valence electrons is marked by a big jump in ionization enthalpy.

(d) Removal of the electron from orbitals bearing lower value is easier than from orbital having higher value.

Q 37 | Page 95

Considering the elements B, Al, Mg, and K, the correct order of their metallic character is:

(a) B > Al > Mg > K

(b) Al > Mg > B > K

(c) Mg > Al > K > B

(d) K > Mg > Al > B

Q 38 | Page 95

Considering the elements B, C, N, F, and Si, the correct order of their non-metallic character is:

(a) B > C > Si > N > F

b) Si > C > B > N > F

(c) F > N > C > B > Si

d) F > N > C > Si > B

Q 39 | Page 95

Considering the elements F, Cl, O and N, the correct order of their chemical reactivity in terms of oxidizing property is:-

(a) F > Cl > O > N

(b) F > O > Cl > N

(c) Cl > F > O > N

(d) O > F > N > Cl

Q 40 | Page 95

NCERT Chemistry Class 11 Part 1

Chemistry Textbook for Class 11 Part 1
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