Transition Metals

Question 1

What is a transition metal?

Answer 1

Transition metals are d block elements that can form at least one stable ion with an incomplete d sub-level.

Question 2

What are variable oxidation states?

Answer 2

Transition metals can form a number of stable ions, each with the metal in a different oxidation state.

Question 3

What is a ligand?

Answer 3

A ligand is any atom, ion or molecule which can donate a pair of electrons to a metal ion. Ligands are Lewis bases and nucleophiles.

Question 4

How are ligands classified?

Answer 4

Ligands are classified by the number of dative covalent or coordinate bonds that they can make.

Question 5

What is an example of a unidentate ligand?

Answer 5

Water molecules frequently act as ligands, making a single bond with the metal ion.

Question 6

What is a multidentate ligand?

Answer 6

Multidentate ligands contain more than two atoms that donate pairs of electrons to form coordinate bonds.

Question 7

What does EDTA 4– do?

Answer 7

EDTA 4– forms six coordinate bonds with a metal ion, forming chelates.

Question 8

What are bidentate ligands?

Answer 8

Bidentate ligands contain two atoms that donate pairs of electrons to form coordinate bonds.

Question 9

Fill in the blank: The coordination number is the number of _______ to the metal ion.

Answer 9

coordinate bonds

Question 10

What is a complex?

Answer 10

A complex consists of a central metal ion surrounded by ligands forming coordinate bonds with the ion.

Question 11

What is the coordination number for an octahedral complex?

Answer 11

6

Question 12

What is cis-trans isomerism?

Answer 12

Cis–trans isomerism occurs because the ligands cannot rotate around the central metal ion.

Question 13

True or False: Different stereoisomers can have different chemical properties.

Answer 13

True

Question 14

What is optical isomerism?

Answer 14

Optical isomerism is when a molecule can exist as two forms that are non-superimposable mirror images of each other.

Question 15

What happens when light is absorbed by transition metal complexes?

Answer 15

Electrons can be promoted to higher energy levels, requiring absorption of specific light frequencies.

Question 16

What factors influence the color of transition metal ions?

Answer 16

• Coordination number
• Ligand type
• Oxidation state

Question 17

What is the ground state in terms of electron energy levels?

Answer 17

The ground state is the lowest energy level (n=1).

Question 18

What does E = hc represent?

Answer 18

E is the energy of the photon.

Question 19

What is the formula for the relationship between frequency and wavelength?

Answer 19

v = c/λ

Question 20

What is the significance of ultraviolet-visible spectroscopy?

Answer 20

It can be used to determine the concentration of substances.

Question 21

When Fe2+ is in a complex what colour is it?

Answer 21

Green

Question 22

What colour is Cu2+ when in a metal ion complex?

Answer 22

Blue

Question 23

What colour is Fe3+ when in a metal ion complex?

Answer 23

Yellow

Question 24

What colour is Al 3+ when in a metal ion complex?

Answer 24

Colourless

Question 25

What is Ligand Substitution?

Answer 25

Process where one ligand is replaced by another.

Question 26

What happens when you decrease ligand number during ligand substitution?

Answer 26

Decrease in coordination number means increase in enthalpy change.

Question 27

[M(H2O)6]2+(aq) + H2O(l)

Answer 27

M(H2O)5(OH)]+(aq) + H3O+(aq)

Question 28

[M(H2O)6]²⁺ + 2OH⁻ →

Answer 28

[M(OH)2(H20)4] + 6H2O

Question 29

Cu(OH)₂(s) + 4NH₃(aq) →

Answer 29

[Cu(NH₃)₄(H₂O)₂]²⁺(aq) + 2OH⁻(aq) (deep blue solution)