General Properties of the Transition Elements (d-Block)

The transition elements share a family of characteristic properties that set them apart from the $s$- and $p$-block elements — properties that trace directly back to their partly filled $(n-1)d$ subshell. Before looking at the properties one by one, it is worth being clear about the scope: a rigorous treatment across all three transition series (3$d$, 4$d$, 5$d$) would require comparing 30 elements in detail, so the discussion that follows is restricted to the first transition series (Sc to Zn, the 3$d$ series), with occasional comparisons drawn to the 4$d$ and 5$d$ series where a trend is instructive.

What This Covers

Taking the elements Sc ($Z=21$) through Zn ($Z=30$) as the reference set, the sections ahead examine, in turn:

• their physical properties — metallic character, lattice structure, melting and boiling points, and density;
• the variation in atomic and ionic size across the series, and how it compares between the 3$d$, 4$d$ and 5$d$ series;
• the trend in ionisation enthalpy along the series, including the successive (first, second, third) ionisation enthalpies; and
• the wide range of oxidation states these elements display, and why that range is so much broader than what is seen among non-transition elements. …