Transision elements

Question 1

What makes an element a transition metal?

Answer 1

They have partially filled d subshells as atoms or ions

Question 2

What elements in the d-block have full d subshells?

Answer 2

Zinc, Cadmium and mercury

Form 2+ ions by losing electrons in the 4s subshell, leaving the 3d full

Question 3

Why can transition metals have multiple oxidation states?

Answer 3

The first ionisation energies are close together, so one or all the electrons could be removed

Question 4

What is coordination number?

Answer 4

Total number of points at which a central atom or ion attaches ligands

Question 5

Coordination sphere

Answer 5

The region surrounding the central atom/ion with the ligands

Question 6

Shape of complex ion with coordination number 6

Answer 6

Octahedral

Question 7

When is a complex ion with coordination number 4 tetrahedral?

Answer 7

When electrons are spin free

Question 8

When is a complex ion with coordination number 4 square planar?

Answer 8

When electrons are spin paired

Question 9

Shape of complex ion with coordiantion number 2?

Answer 9

Linear

Question 10

Bidentate ligand

Answer 10

Ligand with two lone pairs that can bond to the central atom

Question 11

Why are paired electrons in an orbital at a higher energy than those in singly occupied orbitals?

Answer 11

Due to the repulsion, more energy is needed to maintain this arrangement

Question 12

What needs to be absorbed in order to see a colour and why?

Answer 12

The colour of the opposite wavelength on the colour wheel, as the other colours will cancel out

Question 13

What causes the d sub-level in transition metal to split?

Answer 13

Ligands form dative bonds with two of the orbitals.

The electrons in these orbitals repel the electrons in the ligands
These orbitals move to a higher energy level to maintain this position

Question 14

Why do transition metals form coloured compounds?

Answer 14

When the d sub-level is split, electrons move between the two energy levels.

When electrons are promoted, they absorb light of a specific wavelength and the opposite wavelength is observed.

Question 15

Most important factor affecting crystal field splitting energy (Δo)

Answer 15

Splitting strength of ligands

Question 16

How does size of atom affect Δo ?

Answer 16

The bigger the atom, the more electrons in the d orbital. Δo increases due to more orbital overlap

Question 17

How does oxidation state affect Δo?

Answer 17

The higher the oxidation state (charge), the closer the ligands are. More repulsion in the orbitals, so greater orbital split

Question 18

What is crystal field splitting energy?

Answer 18

The difference in energy between the two split sub-levels

Question 19

What is spin?

Answer 19

The tendency of electrons to move away from each other

Question 20

Why do high energy splits have a spin paired arrangement?

Answer 20

It is too far for the electron to be permanently elevated to a higher level. More energetically favourable for the electron to remain paired.

energy of split > energy of spin

Question 21

Why do low energy splits have a spin free arrangement?

Answer 21

It is close enough and energetically favourable for the electron to be permanently elevated to a higher level.

energy of spin > energy of split