Tag: d and f block elements

Questions Related to d and f block elements

Choose the correct answer from the alternative given.
Amongst $TiF _6^{2-}$, $CoF$,   $Cu _2$ $Cl _2$ and $NiCl$, which are the colourless species? (atomic number of Ti = 22, Co = 27, Cu = 29, Ni = 28)

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. $CoF _6^{3-}$and $NiCl _4^{2-}$

  2. $TiF _6^{2-}$and $Cu _2Cl _2$

  3. $Cu _2Cl _2$ and $NiCl _4^{2-}$

  4. $TiF _6^{2-}$ and $CoF _6^{ 3-}$

Show answer
Correct Option: B
Explanation:

TiF$ _6^{2-}$ -

The oxidation state of Ti is +4.
Electronic configuration of Ti$^{4+}$ is [Ar] 3d$^0 4s^0$.
So, unpaired e$^-$ s is present in d-orbitals so it is colourless.
Cu$ _2Cl _2$-
The oxidation state of Cu is +1.
Electronic configuration of Cu$^+$ is [Ar] 3d$^{10} 4s^0$.
So, no unpaired d e$^-$ s are present . Hence, the given compound is colourless.

Colour of transition metal ions are due to absorption of some wavelength. This results in:

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. $d-f$ transition

  2. $s-s$ transition

  3. $s-d$ transition

  4. $d-d$ transition

Show answer
Correct Option: D
Explanation:

Colour of transition metal ions are due to absorption of the same wavelength. This results in $d-d$ transition.

The coloured species is ?

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. ${ VCl } _{ 3 }$

  2. ${ VOSO } _{ 4 }$

  3. ${ Na } _{ 3 }{ VO } _{ 4 }$

  4. $[{ V(H } _{ 2 }O) _{ 6 }]{ SO } _{ 4 }{ H } _{ 2 }O$

Show answer
Correct Option: C

Which of the following compounds are coloured due to charge transfer spectra?

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. ${K} _{2}{Cr} _{2}{O} _{7}$

  2. $KMn{O} _{4}$

  3. $Cu{SO} _{4}.5{H} _{2}O$

  4. Both a and b

Show answer
Correct Option: C

Which of the following ion will give colourless aqueous solution ?  

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. $Ni^{2+}$

  2. $Sc^{3+}$

  3. $Cu^{2+}$

  4. $Mn^{3+}$

Show answer
Correct Option: B
Explanation:

Solution:- (B) ${Sc}^{+3}$

Only the ions that have electrons in $d$-orbital and in which $d-d$ transition is possible will be coloured.
Electronic configuration of ${Sc}^{+3} \left( \text{At. no. = 21} \right) - 1 {s}^{2} 2 {s}^{2} 2{p}^{6} 3{s}^{2} 3 {p}^{6}$
Since it do not contains electrons in $d$-orbital and hence will not undergo $d-d$ transition and do not show colour.

Why are the compounds of transition metal generally coloured ?

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. due to s being filled before d (Aufbau principle)

  2. Due to presence of unpaired electron

  3. unfilled d orbital

  4. d-d transition

Show answer
Correct Option: B,D
Explanation:

coloured compound of transition elements is assosiated with partially filled (n-1)d orbitals. the transition metal ions containing unpaired d-electrons undergoes electronic transition from one d-orbital to another. during this d-d transition process the electrons absorb certain energy from the radiation and emit the remainder of energy as colored light. the color of ion is complementary of the color absorbed by it. hence, colored ion is formed due to d-d transition which falls in visible region for all transition elements.

Statement 1: Transition metal compounds are often colored.
Statement 2: They frequently possess partially filled d-orbitals.

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1.

  2. Both the Statement 1 and Statement 2 are correct, but Statement 2 is NOT the correct explanation of Statement 1.

  3. Statement 1 is correct, but Statement 2 is not correct.

  4. Statement 1 is not correct, but Statement 2 is correct.

Show answer
Correct Option: A
Explanation:

Transition metals are often coloured.

reason - they frequently posses partially filled of orbitals.

Salt of which of the elements are mostly blue in colour ?

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. Cu

  2. Zn

  3. Fe

  4. Cr

Show answer
Correct Option: A
Explanation:

$Cu\longrightarrow $ Blue colour

$Zn\longrightarrow $ White colour
$Fe\longrightarrow $ Green colour
$Cr\longrightarrow $ Orange colour

Colour of $Fe^{+2}$ ions is:

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. blue

  2. light green

  3. very dark green

  4. yellow

Show answer
Correct Option: B
Explanation:

Colour of $Fe^{2+}$ is light green.

Due to this many salts having $Fe^{2+}$ ion are also green in colour.
For ex: $FeSO _4$

The silver salts like $AgBr$ and $AgI$ are coloured because of:

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. d-d transition of electrons

  2. charge transfer

  3. polirisation of halid${Ag}^{+}$ by

  4. both (b) and (c)

Show answer
Correct Option: A
Explanation:

The silver salts like$AgBr$ and $AgI$ are colored, the color of transition metal ions is due  to the presence of unpaired electron . The electrons which absorbs radiations of color that from the visible or UV spectrum and undergo transition from ground state to excited state within d-sub shells,so it is d-d transitions of electrons.