First-row d-block elements

First-row d-block elements (Transition Elements) Overview

• The first-row d-block elements are the 10 transition metals from scandium (Sc) to zinc (Zn). These elements occupy the 4th period and the d-block of the periodic table.
• First-row d-block elements or transition metals are unique in their physical and chemical properties due to the filling of the inner d orbitals.

Electronic Configuration

• The filling of the d orbitals begins from Scandium (Sc) and ends at Zinc (Zn) with a completely filled 3d10 configuration.
• These elements can have multiple oxidation states due to the closeness in energy of the 4s and 3d orbitals, with electrons from both orbitals involved in bonding.
• Transition elements’ remarkable feature is their ability to use their d electrons to form dative covalent bonds or coordinate bonds.

Physical Properties

• Transition metals are good conductors of heat and electricity and have high melting and boiling points.
• They are usually hard, strong, and have high densities.
• Transition metals with an incomplete d sub-level in their ground state or a stable ion are often coloured due to d-d electronic transitions.

Chemical Properties

• Transition metals are known for their ability to form a wide variety of complex ions.
• Most of the first-row d-block elements are capable of forming stable ions with different oxidation states.
• They display catalytic properties, e.g: Iron in the Haber process, and Nickle in the hydrogenation of alkenes.
• These elements have a strong tendency to form coordination compounds due to their small sizes, high ionic charges, and availability of d orbitals for bonding.
• They form coloured compounds due to d-d transitions.

In summary, the unique properties of the first-row d-block elements stem largely from the participation of the d orbitals in bonding, which leads to unique physical and chemical properties and rich chemistry.