Periodic Trends in Chemical Properties of Elements
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CHXI03:CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

313178 The electron gain enthalpies of halogens are as follows:
F = –332, Cl = – 349, Br = –324,
\({\rm{I = - 295}}\,{\rm{kJ}}\,{\rm{mo}}{{\rm{l}}^{{\rm{ - 1}}}}\)
The less negative value for F as compared to that of Cl is due to

1 strong electron-electron repulsions in the compact 2-p subshell of F.
2 weak electron-electron repulsions in the bigger 3-p sub shell of Cl
3 smaller electronegativity value of F than Cl
4 both (1) and (2)
CHXI03:CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

313179 The formation of the oxide ion, \({{\rm{O}}^{{\rm{2 - }}}}{\rm{(g),}}\) from oxygen atom requires first an exothermic and then an endothermic step as shown below:
\({\rm{O(g) + }}{{\rm{e}}^{\rm{ - }}} \to {{\rm{O}}^{\rm{ - }}}{\rm{(g);\Delta }}{{\rm{H}}^{\rm{\Theta }}}{\rm{ = - 141}}\;{\rm{kJ}}\;{\rm{mo}}{{\rm{l}}^{{\rm{ - 1}}}}\)
\({{\rm{O}}^{\rm{ - }}}{\rm{(g) + }}{{\rm{e}}^{\rm{ - }}} \to {{\rm{O}}^{{\rm{2 - }}}}{\rm{(g);\Delta }}{{\rm{H}}^{\rm{\Theta }}}{\rm{ = + 780}}\;{\rm{kJ}}\;{\rm{mo}}{{\rm{l}}^{{\rm{ - 1}}}}\)
Thus process of formation of \({{\rm{O}}^{{\rm{2 - }}}}\) in gas phase is unfavourable even though \({{\rm{O}}^{{\rm{2 - }}}}\) is isoelectronic with neon. It is due to the fact that.

1 Oxygen is more electronegative.
2 Addition of electron in oxygen results in larger size of the ion.
3 Electron repulsion outweighs the stability gained by achieving noble gas configuration.
4 \({{\rm{O}}^{\rm{ - }}}\) ion has comparatively smaller size than oxygen atom.
NCERT Exemplar
CHXI03:CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

313180 Adding electron a neutral gaseous atom usually leads to
(i) Liberation of energy
(ii) Formation of anion
(iii) Proton/electron ratio decrease
(iv) Proton/electron ratio increase
Identify the correct statement

1 (i), (iv)
2 (ii), (iii), (iv)
3 (i), (ii), (iv)
4 (i), (ii), (iii)
CHXI03:CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

313181 Which of the following species has the highest electron affinity?

1 F
2 \(\mathrm{O}\)
3 \(\mathrm{O}^{-}\)
4 \(\mathrm{Na}^{+}\)
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CHXI03:CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

313178 The electron gain enthalpies of halogens are as follows:
F = –332, Cl = – 349, Br = –324,
\({\rm{I = - 295}}\,{\rm{kJ}}\,{\rm{mo}}{{\rm{l}}^{{\rm{ - 1}}}}\)
The less negative value for F as compared to that of Cl is due to

1 strong electron-electron repulsions in the compact 2-p subshell of F.
2 weak electron-electron repulsions in the bigger 3-p sub shell of Cl
3 smaller electronegativity value of F than Cl
4 both (1) and (2)
CHXI03:CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

313179 The formation of the oxide ion, \({{\rm{O}}^{{\rm{2 - }}}}{\rm{(g),}}\) from oxygen atom requires first an exothermic and then an endothermic step as shown below:
\({\rm{O(g) + }}{{\rm{e}}^{\rm{ - }}} \to {{\rm{O}}^{\rm{ - }}}{\rm{(g);\Delta }}{{\rm{H}}^{\rm{\Theta }}}{\rm{ = - 141}}\;{\rm{kJ}}\;{\rm{mo}}{{\rm{l}}^{{\rm{ - 1}}}}\)
\({{\rm{O}}^{\rm{ - }}}{\rm{(g) + }}{{\rm{e}}^{\rm{ - }}} \to {{\rm{O}}^{{\rm{2 - }}}}{\rm{(g);\Delta }}{{\rm{H}}^{\rm{\Theta }}}{\rm{ = + 780}}\;{\rm{kJ}}\;{\rm{mo}}{{\rm{l}}^{{\rm{ - 1}}}}\)
Thus process of formation of \({{\rm{O}}^{{\rm{2 - }}}}\) in gas phase is unfavourable even though \({{\rm{O}}^{{\rm{2 - }}}}\) is isoelectronic with neon. It is due to the fact that.

1 Oxygen is more electronegative.
2 Addition of electron in oxygen results in larger size of the ion.
3 Electron repulsion outweighs the stability gained by achieving noble gas configuration.
4 \({{\rm{O}}^{\rm{ - }}}\) ion has comparatively smaller size than oxygen atom.
NCERT Exemplar
CHXI03:CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

313180 Adding electron a neutral gaseous atom usually leads to
(i) Liberation of energy
(ii) Formation of anion
(iii) Proton/electron ratio decrease
(iv) Proton/electron ratio increase
Identify the correct statement

1 (i), (iv)
2 (ii), (iii), (iv)
3 (i), (ii), (iv)
4 (i), (ii), (iii)
CHXI03:CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

313181 Which of the following species has the highest electron affinity?

1 F
2 \(\mathrm{O}\)
3 \(\mathrm{O}^{-}\)
4 \(\mathrm{Na}^{+}\)
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CHXI03:CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

313178 The electron gain enthalpies of halogens are as follows:
F = –332, Cl = – 349, Br = –324,
\({\rm{I = - 295}}\,{\rm{kJ}}\,{\rm{mo}}{{\rm{l}}^{{\rm{ - 1}}}}\)
The less negative value for F as compared to that of Cl is due to

1 strong electron-electron repulsions in the compact 2-p subshell of F.
2 weak electron-electron repulsions in the bigger 3-p sub shell of Cl
3 smaller electronegativity value of F than Cl
4 both (1) and (2)
CHXI03:CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

313179 The formation of the oxide ion, \({{\rm{O}}^{{\rm{2 - }}}}{\rm{(g),}}\) from oxygen atom requires first an exothermic and then an endothermic step as shown below:
\({\rm{O(g) + }}{{\rm{e}}^{\rm{ - }}} \to {{\rm{O}}^{\rm{ - }}}{\rm{(g);\Delta }}{{\rm{H}}^{\rm{\Theta }}}{\rm{ = - 141}}\;{\rm{kJ}}\;{\rm{mo}}{{\rm{l}}^{{\rm{ - 1}}}}\)
\({{\rm{O}}^{\rm{ - }}}{\rm{(g) + }}{{\rm{e}}^{\rm{ - }}} \to {{\rm{O}}^{{\rm{2 - }}}}{\rm{(g);\Delta }}{{\rm{H}}^{\rm{\Theta }}}{\rm{ = + 780}}\;{\rm{kJ}}\;{\rm{mo}}{{\rm{l}}^{{\rm{ - 1}}}}\)
Thus process of formation of \({{\rm{O}}^{{\rm{2 - }}}}\) in gas phase is unfavourable even though \({{\rm{O}}^{{\rm{2 - }}}}\) is isoelectronic with neon. It is due to the fact that.

1 Oxygen is more electronegative.
2 Addition of electron in oxygen results in larger size of the ion.
3 Electron repulsion outweighs the stability gained by achieving noble gas configuration.
4 \({{\rm{O}}^{\rm{ - }}}\) ion has comparatively smaller size than oxygen atom.
NCERT Exemplar
CHXI03:CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

313180 Adding electron a neutral gaseous atom usually leads to
(i) Liberation of energy
(ii) Formation of anion
(iii) Proton/electron ratio decrease
(iv) Proton/electron ratio increase
Identify the correct statement

1 (i), (iv)
2 (ii), (iii), (iv)
3 (i), (ii), (iv)
4 (i), (ii), (iii)
CHXI03:CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

313181 Which of the following species has the highest electron affinity?

1 F
2 \(\mathrm{O}\)
3 \(\mathrm{O}^{-}\)
4 \(\mathrm{Na}^{+}\)
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CHXI03:CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

313178 The electron gain enthalpies of halogens are as follows:
F = –332, Cl = – 349, Br = –324,
\({\rm{I = - 295}}\,{\rm{kJ}}\,{\rm{mo}}{{\rm{l}}^{{\rm{ - 1}}}}\)
The less negative value for F as compared to that of Cl is due to

1 strong electron-electron repulsions in the compact 2-p subshell of F.
2 weak electron-electron repulsions in the bigger 3-p sub shell of Cl
3 smaller electronegativity value of F than Cl
4 both (1) and (2)
CHXI03:CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

313179 The formation of the oxide ion, \({{\rm{O}}^{{\rm{2 - }}}}{\rm{(g),}}\) from oxygen atom requires first an exothermic and then an endothermic step as shown below:
\({\rm{O(g) + }}{{\rm{e}}^{\rm{ - }}} \to {{\rm{O}}^{\rm{ - }}}{\rm{(g);\Delta }}{{\rm{H}}^{\rm{\Theta }}}{\rm{ = - 141}}\;{\rm{kJ}}\;{\rm{mo}}{{\rm{l}}^{{\rm{ - 1}}}}\)
\({{\rm{O}}^{\rm{ - }}}{\rm{(g) + }}{{\rm{e}}^{\rm{ - }}} \to {{\rm{O}}^{{\rm{2 - }}}}{\rm{(g);\Delta }}{{\rm{H}}^{\rm{\Theta }}}{\rm{ = + 780}}\;{\rm{kJ}}\;{\rm{mo}}{{\rm{l}}^{{\rm{ - 1}}}}\)
Thus process of formation of \({{\rm{O}}^{{\rm{2 - }}}}\) in gas phase is unfavourable even though \({{\rm{O}}^{{\rm{2 - }}}}\) is isoelectronic with neon. It is due to the fact that.

1 Oxygen is more electronegative.
2 Addition of electron in oxygen results in larger size of the ion.
3 Electron repulsion outweighs the stability gained by achieving noble gas configuration.
4 \({{\rm{O}}^{\rm{ - }}}\) ion has comparatively smaller size than oxygen atom.
NCERT Exemplar
CHXI03:CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

313180 Adding electron a neutral gaseous atom usually leads to
(i) Liberation of energy
(ii) Formation of anion
(iii) Proton/electron ratio decrease
(iv) Proton/electron ratio increase
Identify the correct statement

1 (i), (iv)
2 (ii), (iii), (iv)
3 (i), (ii), (iv)
4 (i), (ii), (iii)
CHXI03:CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

313181 Which of the following species has the highest electron affinity?

1 F
2 \(\mathrm{O}\)
3 \(\mathrm{O}^{-}\)
4 \(\mathrm{Na}^{+}\)
NEET DIGITAL LIBRARY