A2-Level Transition Elements

  • Transition metals form at least one stable ion with a partially filled d-subshell

  • Even though not all transition metals behave identically, most share the following properties:

    • High melting and boiling points (compared to S-block metals)

    • Relatively low reactivity (compared to S-block metals)

    • Multiple oxidation states

    • Form complex ions

    • Form coloured compounds

    • Can act as catalysts

QUICK NOTES

Transition Elements

 

There are various definitions for transition elements, but the most commonly accepted definition is ‘an element that can form at least one stable ion with a partially filled d-subshell’.


A transition element will lose electrons to form a positive ion. The positive ion will have an electron configuration that does not have completely filled d-orbitals.

 

 

 

 

 

 

 

 

 

Although different transition elements do not behave identically, most have the following properties.

 

High melting and boiling points (compared to s-block metals)

The metals in the d-block have a greater nuclear charge than the s-block metals; as a result the metallic bonding between d-block metal atoms is stronger. Stronger metallic bonding requires greater energy to overcome.

 

Relatively low reactivity (compared to s-block metals)

Due to the greater nuclear charge of d-block metals, outer electrons are held more tightly in the atom compared to s-block metals and are harder to lose.  This makes the metals less reactive and, unlike s-block metals, they do not react with cold water.

 

Multiple oxidation states

Due to the large number (five) of d-orbitals, there are multiple ways to arrange different numbers of electrons around the nucleus – some ways are more stable than others. This means some transition metals can lose different numbers of electrons to form ions with different stabilities. If a metal atom loses different numbers of electrons, it forms ions with different charges – this is gives rise to multiple oxidation states.

 

Form complex ions

Transition element complexes form when electron rich species surround positive metal ions and form co-ordinate bonds with them. The electron rich species forming co-ordinate bonds with positive ions are called ligands.

 

Form coloured compounds

D-orbitals in the metal ion can be split into high and low energies, the energy gap that exists between the high and low energy orbitals gives rise to coloured compounds. As the d-orbitals split differently in different metals, different colours arise.

 

The ability to act as catalysts

Multiple oxidation states allows a lot of transition metals to act as catalysts, as they are able to lose and gain electrons in different steps during a reaction,  before re-forming their original ion at the end.