Transition Metal
Transition metals are the elements in Groups 3–12 of the periodic table (the d-block), defined by IUPAC as elements with an incomplete d subshell in at least one common oxidation state. They are characterised by high melting points, high densities, variable oxidation states, the ability to form coloured compounds and complex ions, and catalytic activity. Transition metals are industrially critical: iron is the basis of steel, copper is used in electrical wiring, and platinum-group metals serve as catalysts in automotive converters and fuel cells.
Key Formula
[Ar] 3d(1-10) 4s(0-2)
LaTeX: [\text{Ar}]\,3d^{1-10}\,4s^{0-2}
| Symbol | Meaning | Unit |
|---|---|---|
| [Ar] | Argon core electron configuration | — |
| 3d | d subshell being filled across the block | — |
| 4s | s subshell in period 4 | — |
Worked Example
Problem
Write the electron configuration of iron (Fe, atomic number 26) and identify its common oxidation states.
Solution
Step 1 – Full configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s² Step 2 – Abbreviated: [Ar] 3d⁶ 4s² Step 3 – Fe²⁺ (ferrous): remove two 4s electrons → [Ar] 3d⁶ Step 4 – Fe³⁺ (ferric): remove two 4s and one 3d electron → [Ar] 3d⁵ Note: Fe³⁺ has a half-filled d shell (3d⁵), which is particularly stable due to exchange energy.
Answer
Fe: [Ar] 3d⁶ 4s²; common oxidation states are +2 (Fe²⁺) and +3 (Fe³⁺)
Common transition metals and their properties
| Element | Symbol | Key Oxidation States | Colour of Ion in Water | Key Use |
|---|---|---|---|---|
| Iron | Fe | +2, +3 | Fe²⁺ pale green, Fe³⁺ yellow | Steel production |
| Copper | Cu | +1, +2 | Cu²⁺ blue | Electrical wiring |
| Chromium | Cr | +2, +3, +6 | Cr³⁺ green | Stainless steel, plating |
| Manganese | Mn | +2, +4, +7 | Mn²⁺ pale pink | Batteries, alloys |
| Zinc | Zn | +2 | Colourless | Galvanising, alloys |
Interactive Tools
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Related Terms
Chemical Group
A chemical group (also called a family) is a vertical column in the periodic table containing elements that share the same number of valence electrons, and therefore exhibit similar chemical properties and reactivity patterns. The modern IUPAC system numbers groups 1 through 18 from left to right. Elements within a group show predictable trends: for example, reactivity increases down Group 1 (alkali metals) because the outermost electron is progressively further from the nucleus and more easily lost.
Periodic Table
The periodic table is a tabular arrangement of all known chemical elements ordered by increasing atomic number, with elements having similar chemical properties placed in vertical columns called groups. It was developed by Dmitri Mendeleev in 1869 and serves as the foundational reference for all of chemistry. The table reveals periodic trends in elemental properties such as atomic radius, ionisation energy, and electronegativity, enabling scientists to predict the behaviour of elements and their compounds.
Periodic Trend
Periodic trends are systematic patterns in elemental properties that arise from the regular variation in nuclear charge and electron configuration across periods and down groups of the periodic table. Key periodic trends include atomic radius, ionisation energy, electron affinity, electronegativity, and metallic character, all of which change predictably as atomic number increases. Understanding periodic trends allows chemists to predict chemical reactivity, bond types, and physical properties of elements and their compounds without needing to memorise individual data for every element.
From Latin "transire" (to go across, to pass through). The term "transition" was coined because these elements bridge the highly electropositive s-block metals on the left and the electronegative p-block nonmetals on the right of the periodic table, exhibiting intermediate properties.