Transition Elements: Properties Explained with Exceptional Cases

Have you ever wondered why iron is used to make steel, why copper conducts electricity so well, or why some metal compounds are brightly coloured? The answer lies in a special group of elements called transition elements. These elements occupy the middle section of the periodic table and possess unique properties due to their partially filled d-orbitals. 

This article provides the insights into what transition elements are, their electronic configuration and applications in daily life and industries. 

Table of Contents 

• What are Transition Elements
• Position of Transition Elements in the Periodic Table
• Electronic Configuration of Transition Elements
• Some Exceptional Cases of Transition Elements
• General Properties of Transition Elements
• Major Trends of Transition Elements
• Uses of Transition Elements

What are Transition Elements

Transition elements are the elements that have partially filled d-orbitals in their atoms or in one of their oxidation states.

According to the IUPAC definition, a transition element is:

An element that has an incomplete d-subshell or forms one or more stable ions with an incomplete d-subshell.

In simple words, these elements contain electrons in the d-orbitals and show special properties such as:

• Variable oxidation states
• Formation of coloured compounds
• Magnetic behaviour
• Catalytic activity
• Formation of complex compounds

Position of Transition Elements in the Periodic Table

Transition elements are present in the d-block of the periodic table, which includes:

Groups 3 to 12

They are located between the s-block and p-block elements.

The transition series are:

Series	Period
First Transition Series	3d Series
Second Transition Series	4d Series
Third Transition Series	5d Series

The lanthanides and actinides belong to the f-block and are known as inner transition elements.

Electronic Configuration of Transition Elements

The general electronic configuration of transition elements is:

(n−1)d1−10ns0−2

First Transition Series

Element	Atomic Number	Electronic Configuration
Sc	21	[Ar] 3d¹4s²
Ti	22	[Ar] 3d²4s²
V	23	[Ar] 3d³4s²
Cr	24	[Ar] 3d⁵4s¹
Mn	25	[Ar] 3d⁵4s²
Fe	26	[Ar] 3d⁶4s²
Co	27	[Ar] 3d⁷4s²
Ni	28	[Ar] 3d⁸4s²
Cu	29	[Ar] 3d¹⁰4s¹
Zn	30	[Ar] 3d¹⁰4s²

Some Exceptional Cases of Transition Elements 

Why do Chromium and Copper have Exceptional Configurations?

Chromium and copper do not completely follow the Aufbau principle because:

• Half-filled d-orbitals are more stable.
• Completely filled d-orbitals are also highly stable.

Therefore:

Cr=[Ar]3d54s1Cu=[Ar]3d104s1

Why are Zinc, Cadmium and Mercury Not Transition Elements?

Although Zn, Cd and Hg belong to the d-block, they are not considered transition elements.

This is because they have:

(n−1)d10ns2

configuration and their ions also contain completely filled d-orbitals.Therefore, they do not show the typical properties of transition elements.

General Properties of Transition Elements

Transition elements possess several unique characteristics.

1. Variable Oxidation States

They exhibit different oxidation states because both ns and (n−1)d electrons participate in bonding.

Examples:

• Iron: +2, +3
• Manganese: +2 to +7
• Chromium: +2, +3, +6

2. Formation of Coloured Compounds

Most transition metals form coloured ions because electrons can move between different d-orbitals by absorbing light energy.

Examples:

Compound	Colour
CuSO₄	Blue
K₂Cr₂O₇	Orange
KMnO₄	Purple

3. Paramagnetic Nature

Transition elements usually contain unpaired electrons.

Therefore, many of them are attracted by magnetic fields and show paramagnetism.

Examples:

• Iron
• Nickel
• Cobalt

4. Formation of Complex Compounds

Transition metals can combine with molecules or ions called ligands to form coordination compounds.

Examples:

[Fe(CN)6]4−[Cu(NH3)4]2+

5. High Melting and Boiling Points

Transition elements possess:

• Strong metallic bonding
• Participation of d-electrons in bonding

Therefore, they generally have high melting and boiling points.

6. High Density and Hardness

Most transition metals are:

• Hard
• Strong
• Dense

Examples:

• Iron
• Nickel
• Chromium

7. Good Conductors of Heat and Electricity

The presence of delocalised electrons makes transition metals excellent conductors.

Examples:

• Copper
• Silver
• Gold

Major Trends of Transition Elements 

Atomic Radius of Transition Elements 

The atomic size decreases slightly from Group 3 to Group 6 because:

• Nuclear charge increases.
• d-electrons provide poor shielding.

From Group 7 onwards, the sizes remain almost constant because Electron-electron repulsions balance the increasing nuclear charge.Down the group, the atomic radius increases due to the addition of electron shells.

Also Read: Atomic Radius in Periodic Table 

 Ionisation Enthalpy of Transition Elements

Ionisation enthalpy is the energy required to remove an electron from an atom.

Transition elements generally have:

• Higher ionisation energies than s-block elements.
• Gradual increase across the period.

This is because of:

• Increasing nuclear charge
• Smaller atomic size

Catalytic Properties of Transition Elements

Many transition metals act as catalysts because:

• They show variable oxidation states.
• They can form intermediate compounds.

Examples:

Catalyst	Process
Iron	Haber Process
Vanadium Pentoxide (V₂O₅)	Contact Process
Nickel	Hydrogenation of oils

Uses of Transition Elements

1. Iron (Fe): Used in steel manufacturing and construction.
2. Copper (Cu): Used in electrical wires and electronic devices.
3. Chromium (Cr): Used in stainless steel and metal plating.
4. Nickel (Ni): Used in batteries and coins.
5. Titanium (Ti): Used in aircraft and medical implants.
6. Platinum (Pt): Used in jewellery and catalytic converters.
7. Industrial Importance: Many transition elements act as catalysts and are valued for their high melting and boiling points.

Also Read: 118 Elements Their Symbols and Atomic Size

Transition elements are among the most important elements in chemistry because of their unique electronic configurations and remarkable properties. Their ability to show variable oxidation states, form coloured compounds, exhibit magnetic behaviour and act as catalysts makes them essential in industries and everyday life. From iron used in construction to copper in electrical wiring and platinum in catalytic converters, transition elements have countless applications.