The d- and f-Block Elements

Lesson

Part 1 — the metals in the middle of the periodic table: why they are hard, coloured, magnetic and good catalysts.

In this lesson you will

Locate the d- and f-block elements in the periodic table and define a transition element
Write the electronic configurations of 3d elements and their ions, explaining the chromium and copper anomalies
Explain the trends in radius, ionisation enthalpy, oxidation states and E° values across the 3d series
Calculate spin-only magnetic moments and explain colour, catalytic activity, interstitial compounds and alloy formation

Schematic: element symbols are left out so that the blocks stand out.

Concept

Where are the d- and f-block elements?

The d-block fills groups 3–12 in periods 4–7, giving the 3d, 4d, 5d and 6d series. A transition element has an incompletely filled d subshell in the atom or in one of its common ions. Zinc, cadmium and mercury have full $d^{10}$ shells in the atom and in their common ions, so they are not regarded as transition elements, though they are d-block elements.

Table of the four d-series with their period, first and last elements and the d orbitals being filled
Series	Period	Elements	d orbitals filled
3d	4	Sc to Zn	3d
4d	5	Y to Cd	4d
5d	6	La, Hf to Hg	5d
6d	7	Ac, Rf to Cn	6d

Concept

Electronic configurations of the 3d series

General configuration: $(n-1)d^{1\text{–}10}\, ns^{1\text{–}2}$ . Chromium and copper are exceptions: a half-filled ( $d^5$ ) or completely filled ( $d^{10}$ ) d subshell has extra stability, and the 3d and 4s energies are very close.

Table of the electronic configurations of the 3d elements from scandium to zinc, with chromium 3d5 4s1 and copper 3d10 4s1
Element	Configuration	Element	Configuration
Sc	$[\text{Ar}]3d^1 4s^2$	Fe	$[\text{Ar}]3d^6 4s^2$
Ti	$[\text{Ar}]3d^2 4s^2$	Co	$[\text{Ar}]3d^7 4s^2$
V	$[\text{Ar}]3d^3 4s^2$	Ni	$[\text{Ar}]3d^8 4s^2$
Cr	$[\text{Ar}]3d^5 4s^1$	Cu	$[\text{Ar}]3d^{10} 4s^1$
Mn	$[\text{Ar}]3d^5 4s^2$	Zn	$[\text{Ar}]3d^{10} 4s^2$

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