Question

Arrange the following in the decreasing order of property indicated:
(i) F, Cl, Br and I (electron affinity)
(ii) Mg, Al, Si and Na (ionization energy)
(iii) C, N, O and F (second ionization energy)

Answer 1

Explanation:

S

1

:Na

2

O

2

<MgO<ZnO<P

4

O

10

: as non-metallic character increases the acidic character increases, MgO,Na

2

O are basic, ZnO amphoteric and P

4

O

10

acidic.

S

2

: Mg has a higher first ionization energy than Na due to a small size and higher nuclear charge. Mg has higher than Al because of ns

2

configuration (has extra stability and high electron penetration power of s-subshell electrons) and Si has higher than Al because of higher nuclear charge and small size. IE

1

:Na=496,Al=577,Mg=737 and Si=786 kJ/mole.

S

3

: There is more interelectronic repulsion in 2p-subshell of fluorine than chlorine (3p). So extra electron will be added easily in 3p-subshell of chlorine as compared to 2p-subshell of fluorine. Down the group electron affinity values generally decreases with increasing atomic number due to increase in atomic size. So Cl>F>Br.