Topic 13.1: The transition metals – First-row d-block elements
The transition elements have characteristic properties; these properties are related to their all having incomplete d sublevels.
• Understanding: Transition elements have variable oxidation states, form complex ions with ligands, have coloured compounds,
and display catalytic and magnetic properties.
▪ Transition elements: element that has an atom with an incomplete d-sublevel or give rise to cation with incomplete d-sublevels
• Variable oxidation states: transition metals have variable oxidation states (e.g. +2, +7 in manganese)
• Forms complex ions with ligands:
• Coloured compounds:
• Catalytic property: can catalyst various reaction (e.g. Haber process, oxidation of alcohol, hydrogenation of alkenes)
• Magnetic property: dependent on their oxidation state and coordinate number
▪ Inner transition element: f-block elements (lanthanoids and actinoids)
• Understanding: Zn is not considered to be a transition element as it does not form ions with incomplete d-orbitals.
▪ Group 12 elements: not considered transition elements as all d-sublevels are full and do not form ions with incomplete orbitals
• Understanding: Transition elements show an oxidation state of +2 when the s-electrons are removed.
▪ All transition elements show an oxidation state of +2
• This is because electrons in the 4s2 orbitals get removed first
Type A elements Type B elements Type C elements
Consists of scandium, titanium chromium, iron, cobalt, nickel,
and vanadium manganese copper, zinc
Oxidation Stable high Stable high Unstable high
states Unstable low Stable low Stable low
Example V +5 in VO3- Mn +7 in MnO4- Fe +2 [Mn(H2O)6]2+
Mn +2 [Mn(H2O)6]2+
• Applications and skills: Explanation of the ability of transition metals to form variable oxidation states from successive ionization
energies.
▪ Successive ionization energies in transition metals: 3d and 4s electrons have similar successive ionization energies
• 3d orbitals and 4s orbitals are placed on a similar energy level
• The successive ionization energy is gradual as there is less repulsion every time an electron is removed
• +2 oxidation state: removal of electrons of 4s orbital; ionization energy is same for most
• Other oxidation state: removal of electrons further to form a stable 3d orbitals (empty, half-full or full)
• Applications and skills: Explanation of the nature of the coordinate bond within a complex ion.
▪ Transition metal complex: compounds that contain transition metal ion
is bonded (coordinate bond) to a group of ligands
• Complex ion: charged transition metal complex; the charge
on the ion is delocalized over the entire complex
• Coordinating bonding: coordinate bonds exist between
ligands and the central metal ion (determines geometry)
• Coordination number: number of ligands attached in a
transition metal complex
▪ Ligand: molecule or ion that contains a non-bonding electron pair
forming coordinate bonds to a central metal ion in a complex
• Proligand: term used to describe a species that can act as a
ligand but is not yet coordinated
• Monodentate ligands: contribute one lone pair to the
coordinate bond in a complex (e.g. Cl-, H2O)
• Polydentate ligands: contribute more than one lone pair to the
coordinate bond in a complex (e.g. en, EDTA)
• Applications and skills: Explanation of the magnetic properties in transition metals in terms of unpaired electrons.
Paramagnetic materials Diamagnetic materials
Description Contain unpaired d electrons and are attracted by an Contain paired d electrons and are repelled by an
external magnetic field external magnetic field
Strength Dependent on number of unpaired electrons Paired electrons cancel out each other’s magnetic
field; no net magnetic moment
Example All atoms apart from Zn, Mg2+, Co2-, Ni2+, Fe2+ Zn, Zn2+
The transition elements have characteristic properties; these properties are related to their all having incomplete d sublevels.
• Understanding: Transition elements have variable oxidation states, form complex ions with ligands, have coloured compounds,
and display catalytic and magnetic properties.
▪ Transition elements: element that has an atom with an incomplete d-sublevel or give rise to cation with incomplete d-sublevels
• Variable oxidation states: transition metals have variable oxidation states (e.g. +2, +7 in manganese)
• Forms complex ions with ligands:
• Coloured compounds:
• Catalytic property: can catalyst various reaction (e.g. Haber process, oxidation of alcohol, hydrogenation of alkenes)
• Magnetic property: dependent on their oxidation state and coordinate number
▪ Inner transition element: f-block elements (lanthanoids and actinoids)
• Understanding: Zn is not considered to be a transition element as it does not form ions with incomplete d-orbitals.
▪ Group 12 elements: not considered transition elements as all d-sublevels are full and do not form ions with incomplete orbitals
• Understanding: Transition elements show an oxidation state of +2 when the s-electrons are removed.
▪ All transition elements show an oxidation state of +2
• This is because electrons in the 4s2 orbitals get removed first
Type A elements Type B elements Type C elements
Consists of scandium, titanium chromium, iron, cobalt, nickel,
and vanadium manganese copper, zinc
Oxidation Stable high Stable high Unstable high
states Unstable low Stable low Stable low
Example V +5 in VO3- Mn +7 in MnO4- Fe +2 [Mn(H2O)6]2+
Mn +2 [Mn(H2O)6]2+
• Applications and skills: Explanation of the ability of transition metals to form variable oxidation states from successive ionization
energies.
▪ Successive ionization energies in transition metals: 3d and 4s electrons have similar successive ionization energies
• 3d orbitals and 4s orbitals are placed on a similar energy level
• The successive ionization energy is gradual as there is less repulsion every time an electron is removed
• +2 oxidation state: removal of electrons of 4s orbital; ionization energy is same for most
• Other oxidation state: removal of electrons further to form a stable 3d orbitals (empty, half-full or full)
• Applications and skills: Explanation of the nature of the coordinate bond within a complex ion.
▪ Transition metal complex: compounds that contain transition metal ion
is bonded (coordinate bond) to a group of ligands
• Complex ion: charged transition metal complex; the charge
on the ion is delocalized over the entire complex
• Coordinating bonding: coordinate bonds exist between
ligands and the central metal ion (determines geometry)
• Coordination number: number of ligands attached in a
transition metal complex
▪ Ligand: molecule or ion that contains a non-bonding electron pair
forming coordinate bonds to a central metal ion in a complex
• Proligand: term used to describe a species that can act as a
ligand but is not yet coordinated
• Monodentate ligands: contribute one lone pair to the
coordinate bond in a complex (e.g. Cl-, H2O)
• Polydentate ligands: contribute more than one lone pair to the
coordinate bond in a complex (e.g. en, EDTA)
• Applications and skills: Explanation of the magnetic properties in transition metals in terms of unpaired electrons.
Paramagnetic materials Diamagnetic materials
Description Contain unpaired d electrons and are attracted by an Contain paired d electrons and are repelled by an
external magnetic field external magnetic field
Strength Dependent on number of unpaired electrons Paired electrons cancel out each other’s magnetic
field; no net magnetic moment
Example All atoms apart from Zn, Mg2+, Co2-, Ni2+, Fe2+ Zn, Zn2+
