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Classification Of Elements And Periodicity In Properties

Q: There are four elements p, q, r and s having atomic numbers \$Z-1\$, \$Z\$, \$Z+1\$ and \$Z+2\$ respectively. If the element q is an inert gas, select the correct statements:(i) p has most negative electron gain enthalpy in the respective period.(ii) r is an alkali metal.(iii) s exists in +2 oxidation state.

As 'q' is a noble gas, p, r and s having atomic number \$Z-1\$, \$Z+1\$ and \$Z+2\$ should belong to halogen, alkali metal and alkaline earth metal respectively. As halogen has one electron less than stable noble gas configuration, it has a greater tendency to accept an additional electron forming an anion. Alkaline earth metal having valence shell configuration \$ns^{2}\$ exists in \$+2\$ oxidation state.

Q: The order of first electron affinity of \$O, S\$ and \$Se\$ is:

O has an exceptionally smaller value of electron affinity \$(-141\ kJmol^{-1})\$ due to smaller atomic size than sulphur (weaker electron-electron repulsion in 3p-subshell). It is less than Se and Te also.\$ S>Se>O\$Thus, Option B is correct.

Q: Beryllium and aluminium exhibit many properties which are similar. But, the two elements differ in:

Beryllium and aluminum exhibit many properties that are similar. But, the two elements differ in exhibiting maximum covalency in compounds.For example \$Be\$ forms \$BeCl_2\$ and \$Al\$ forms \$AlCl_3\$.\$Be\$ and \$Al\$ shows some similarities due to the diagonal relationship. Some of these include the following.They form polymeric hydrides.Their halides are covalent. Both \$Be\$ and \$Al\$ form covalentcompounds.Their oxides are amphoteric in nature.\$BeO+2HCl \rightarrow BeCl_2 + H_2O\$\$BeO + 2NaOH \rightarrow Na_2BeO_2+H_2O\$\$Al_2O_3+6HCl \rightarrow 2AlCl_3 +3H_2O\$\$Al_2O_3 +2NaOH \rightarrow 2NaAlO_2 + H_2O\$

Q: The process(es) requiring the absorption of energy is(are) :

A) When a neutral chlorine atom accepts an electron to from chloride anion, energy is released which is equal to the electron affinity of chlorine.B) When an electron is added to \$O^-\$ anion to form \$O^{2-}\$ ion, energy is required to overcome the force of repulsion. Thus, the second electron affinity of oxygen is an endoergic process. It is equal to +780 kJ/mol.C) When Fe(III) ion accepts an electron to form Fe(II) ion, energy is released.D) When an argon atom accepts an electron to form \$Ar^-\$ anion, energy is required as the stable configuration \$(ns^2np^6)\$ is broken.

Q: Select equation(s) having endothermic step:

\$(A) O^-(g) \rightarrow O^{2-}(g) ; \Delta H_{e.g.} = (+)ve\$\$(B) Na^+(g) + CI^- (g) \rightarrow Na^+ CI^- (s) ; \Delta H_{I.E.} = (-)ve\$\$(C) N(g) \rightarrow N^-(g) ; \Delta H_{e.g.} = (+)ve\$\$(D) Al^{2+}(g) \rightarrow Al^{3+}(g) ; \Delta H_{I.E.} = (+)ve\$

Q: Which among the following factors is the most important in making fluorine the strongest oxidising agent?

Fluorine is the strongest oxidizing agent due to low heat of dissociation and high heat of hydration which compensate the lower value of electron affinity.

Q: Statement-1 : Electron affinity of fluorine is less than that of chlorine.Statement-2 : Chlorine can accommodate an electron by utilising its vacant 3d-orbital.

The electron affinity of fluorine is less than chlorine because fluroine is exceptionally small in size because of which energy has to be supplied to introduce an extra electron to overcome the electronic repulsions between the incoming electron and the electrons already present.

Q: The electron gain enthalpies of halogens in kJ mol\$^{-1}\$ are as given as F = -332, Cl = -349, Br = -324, I = -295. The less negative value for F as compared to that of Cl is due to :

Due to small size of F atom, the electron-electron repulsions in compact 2-p subshell are large and hence the incoming electron is not accepted with the same ease as is the case with Cl (less electron - electron repulsions).

Q: Which of the following represent(s) the correct order of electron affinities ?

Hint: Electron affinity increases across a period and decreases down the group. Explanation:Generally, the electron affinity values of 3rd-period elements are higher than the elements of the 2nd period of the same group because of less inter-electronic repulsions. Atomic size, nuclear charge, and electrons configurations also affect the electron affinity.A) Correct order should be \$Cl>F>Br>I\$, due to the fact that the second-period elements have lower electron affinity than third-period elements in the respective groups.B) Correct order should be \$Cl>F>C>N\$, due to fact above and electron affinities increase across a period. However, \$N O>C>N\$ is the correct order because electron affinities increase across a period. However \$N P>C>N\$ is also a correct order, due to the fact above and because \$N<C\$ because \$N\$ has a stable half-filled configuration.Correct Option: \$C\$ and \$D\$

Q: The species among the following having the highest electron affinity is:

Fluoride and chloride ions have a complete octet configuration. Hence, they are not ready to accept an electron. When adding one more electron to the uninegative oxygen anion, electron-electron repulsion will occur and makes the reaction endothermic. Hence, the oxygen atom has the highest electron affinity among other given options.

Chemistry
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Easy Qs Med Qs Hard Qs

There are four elements p, q, r and s having atomic numbers $Z - 1$ , $Z$ , $Z + 1$ and $Z + 2$ respectively. If the element q is an inert gas, select the correct statements:
(i) p has most negative electron gain enthalpy in the respective period.
(ii) r is an alkali metal.
(iii) s exists in +2 oxidation state.

(i) and (ii) only

(ii) and (iii) only

(i) and (iii) only

(i), (ii) and (iii)

Hard

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The order of first electron affinity of $O, S$ and $S e$ is:

O > S > S e

S > S e > O

S e > O > S

S > O > S e

Hard

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Beryllium and aluminium exhibit many properties which are similar. But, the two elements differ in:

maximum covalency in compounds

forming polymeric hydrides

forming covalent halides

exhibiting amphoteric nature in their oxides

Hard

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The process(es) requiring the absorption of energy is(are) :

C l \to C l^{-}

O^{-} \to O^{2 -}

F e^{3 +} \to F e^{2 +}

A r \to A r^{-}

Hard

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Select equation(s) having endothermic step:

O^{-} (g) \to O^{2 -} (g)

N a^{+} (g) + C l^{-} (g) \to N a C l (s)

N (g) \to N^{-} (g)

A l^{2 +} (g) \to A l^{3 +} (g)

Hard

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Which among the following factors is the most important in making fluorine the strongest oxidising agent?

Electron affinity

Ionisation enthalpy

Hydration enthalpy

Bond dissociation energy

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Statement-1 : Electron affinity of fluorine is less than that of chlorine.
Statement-2 : Chlorine can accommodate an electron by utilising its vacant 3d-orbital.

Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1

Statement-1 is True, Statement-2 is True; Statement-2 is not a correct explanation for Statement-1

Statement-1 is True, Statement-2 is False

Statement-1 is False, Statement-2 is True

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The electron gain enthalpies of halogens in kJ mol $^{- 1}$ are as given as F = -332, Cl = -349, Br = -324, I = -295. The less negative value for F as compared to that of Cl is due to :

strong electron - electron repulsions in the compact 2p-sub shell of F

weak electron - electron repulsions in the bigger 3p-sub shell of Cl

smaller electronegativity value of F than Cl

both (A) and (B)

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Which of the following represent(s) the correct order of electron affinities ?

F > Cl > Br > I

C < N < Cl < F

N < C < O < F

C < Si > P > N

Hard

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The species among the following having the highest electron affinity is:

O

F^{-}

C l^{-}

O^{-}

Hard

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Classification Of Elements And Periodicity In Properties

Chemistry 4872 Views

There are four elements p, q, r and s having atomic numbers Z−1, Z, Z+1 and Z+2 respectively. If the element q is an inert gas, select the correct statements: (i) p has most negative electron gain enthalpy in the respective period. (ii) r is an alkali metal. (iii) s exists in +2 oxidation state.

The order of first electron affinity of O,S and Se is:

Beryllium and aluminium exhibit many properties which are similar. But, the two elements differ in:

The process(es) requiring the absorption of energy is(are) :

Select equation(s) having endothermic step:

Which among the following factors is the most important in making fluorine the strongest oxidising agent?

Statement-1 : Electron affinity of fluorine is less than that of chlorine. Statement-2 : Chlorine can accommodate an electron by utilising its vacant 3d-orbital.

The electron gain enthalpies of halogens in kJ mol−1 are as given as F = -332, Cl = -349, Br = -324, I = -295. The less negative value for F as compared to that of Cl is due to :

Which of the following represent(s) the correct order of electron affinities ?

The species among the following having the highest electron affinity is:

Chemistry
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The order of first electron affinity of $O, S$ and $S e$ is:

Statement-1 : Electron affinity of fluorine is less than that of chlorine.
Statement-2 : Chlorine can accommodate an electron by utilising its vacant 3d-orbital.

The electron gain enthalpies of halogens in kJ mol $^{- 1}$ are as given as F = -332, Cl = -349, Br = -324, I = -295. The less negative value for F as compared to that of Cl is due to :