Chemistry Chapter 23 (Inorganic Chemistry)

Physical Properties of Transition metals

They are

• Hard

• Strong

• Shiny

• High melting point

• High electrical and heat conductivity

Chemical Properties of Transition metals

• They all have 4s electrons as their outer shell, so they have similar chemical properties

• Not a trend in properties like across s- and p- block elements

4 characteristic properties of transition metals

• Their ions are colored (compounds are not white solids/colorless solutions)

• They can form complex ions

• They exhibit catalytic activity (behave as catalysts)

• They have variable oxidation states

Why can transition metals act as catalysts?

Due to their varied oxidation states

n/c

n/c

What is a transition metal?

They are elements which can form stable ions which have a partly filled d orbital

Are all d-block elements transition metals?

No

What 2 elements in the d-block (period 3) are not considered transition metals?

Scandium (Sc) and Zinc(Zn)

What is the ion for scandium?

Sc³⁺

What is the ion for zinc?

Zn²⁺

Which other ion does not exhibit transition metal properties and why?

• Cu⁺

• It has a white colored compound

• It has a filled d- orbital

What is a complex ?

A molecule or ion, consisting of a central metal atom or ion, with a number of molecules or ions(ligands) surrounding it

When is a complex ion formed?

• If the overall complex is charged and the charge is spread over the whole ion

What is a ligand?

Molecule or ion that forms a co-ordinate (dative) bond with a transition metal by donating a pair of electrons to the bond

What is one key feature all ligands must have?

• They must have a lone pair of electrons which donates to the metal ion

What type of bond do ligands form with the metal ion?

• A ligand forms dative bond(s) with the central metal ion

What is a monodentate ligand?

An atom, ion, or molecule that forms one dative covalent (coordinate) bond with a central metal ion by donating one pair of electrons

What are 4 examples of monodentate ligands?

• Cl^-

• H₂O

• NH₃

• CN^-

What is a bidentate ligand?

Atom, ion, or molecule that forms two dative covalent (coordinate) bond with a central metal ion by donating two pairs of electrons

Why do bidentate ligands behave the way they do?

It is because they contain 2 atoms which each have a lone pair of electrons

What are 2 examples of bidentate ligands?

• 1,2-diaminoethane (H₂NCH₂CH₂NH₂)

• Ethanedioate (C₂O₄^2-)

(Examples of these complexes shown in the images)

What are the other names for the 2 common bidentate ligands

• 1,2-diaminoethane (H₂NCH₂CH₂NH₂) →  ‘en’

• Ethanedioate ion (C₂O₄^2- ) →  ‘ox’

Common example of a multidentate ligand

EDTA^4- (Ethylenediaminetetraacetic acid)

What is co-ordination number?

The total number of dative (coordinate) bonds formed between the central metal ion and its surrounding ligands

What does coordination number determine?

It determines the 3D shape of the compound

What is a ligand similar to?

• A nucleophile

What is a Lewis base?

An electron pair donor

Draw the complex ion: [Cu(H2O)6]²⁺

Draw the complex ion: [NiCl4]^2-

What type of complex is [Ag(NH3)2]⁺ ?

Linear Complex

Draw the complex: [Ag(NH3)2]⁺

What reagent is [Ag(NH3)2]⁺ used in?

Tollens Reagent

Why do the energy levels of the electrons of a transition metal in complex split?

This is due to the interference from the lone pairs of electrons donated by the ligand bonded to the central metal ion. The ligands repel electrons on the central metal ion, causing those electrons to have a higher energy level while the other electron’s energy levels are lowered

Why do transition metals have coloured ions?

• It is because when ligands surround the central metal ion, the energy levels of the d- orbital electrons split

• Electrons in the lower energy d orbitals can absorb a certain wavelength of visible light energy and be

excited.

• The energy gap in the d orbitals is ΔE = hc/λ and corresponds to a wavelength in the visible spectrum

• We see the light transmitted (which is not absorbed) so see the complementary colour of the absorbed light (the light is not emitted)

Why do only transition metals form coloured ions?

• All transition metal ions have partly filled d

orbitals

• So they have at least one space for a d electron to

move to AND they have at least one d electron able to be excited

• Complexes of non-transition metals are colourless e.g. Al, Ca, Mg, Zn and Sc