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Transition Elements - Definition, Properties, FAQs

Transition Elements - Definition, Properties, FAQs

Team Careers360Updated on 02 Jul 2025, 04:42 PM IST

Transition elements (also known as transition metals) are elements that have partially filled d-orbitals. IUPAC defines transition elements as an element having a d-subshell that is partially filled with electrons, or an element that can form stable cations with an incompletely filled d orbital. In general, any element that corresponds to the d-block of the modern periodic table (which consists of groups 3-12) is considered to be a transition element. Even the f-block elements comprising the lanthanides and the actinides can be considered as transition elements.

This Story also Contains

  1. Transition Elements-
  2. Some Solved Examples
  3. Conclusion
Transition Elements - Definition, Properties, FAQs
Transition Elements

Several transition metals have catalytic properties that are very useful in the industrial production of some chemicals. For example, iron is used as a catalyst in the Haber process, vanadium pentoxide is used as a catalyst in the industrial production of sulphuric acid. The transition metals exhibit typical metallic properties such as malleability, ductility, high tensile strength, and metallic luster. They are generally good conductors of heat and electricity and tend to crystallize in BCC (body-centered cube), CCP (cubic close-packed), or HCP (hexagonal close-packed) structures. However, trends can be observed in the metallic properties of the transition elements. For example, elements such as chromium and molybdenum are some of the hardest transition metals because they contain many unpaired electrons

Transition Elements-

In the extended form of the periodic table, the elements have been grouped into four blocks namely s, p, d, and f-blocks. The elements belonging to groups 3 to 12 are called d-block or transition elements. In these elements, the last electron enters (n-1) d-subshell. The configuration of these elements is (n−1)d1−10ns1−2. These are present between s-block and p-block elements. The properties of these elements are intermediate between the properties of s-block and p-block elements, i.e., d-block elements represent change or transition in properties from most electropositive s-block elements to least electropositive p-block elements. Therefore, these elements are called transition elements.
Earlier, the transition elements were regarded as those elements that possessed partially filled penultimate d-subshells in their ground state or in one of their commonly occurring oxidation states. This definition included coinage metals(Cu, Ag, and Au) in the transition elements as their ions have partially filled (n-1)d-subshells although their atoms have filled(n-1) d-subshells in the ground state.


However, the above definition does not cover the elements of group 12, i.e. Zn, Cd, and Hg as these elements do not have partially filled (n-1) d-subshells either in the ground state or in ions.

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However, zinc metals showing similarities in some of the chemical properties with transition metals are also included in this block. These are considered as end members of the transition series in order to maintain a rational classification of elements.


Certain d-block elements are particularly important in living organisms. Iron, the transition element, is present in the largest quantity in the human body. The best-known biological iron-containing compound is the protein hemoglobin, the red component of blood that is responsible for the transport of oxygen. Cobalt is the crucial element in vitamin B12, a compound that acts as a catalyst in the metabolism of carbohydrates, fats and proteins. Molybdenum and iron together with sulphur form the reactive portion of nitrogenase, a biological catalyst used by nitrogen-fixing organisms to convert atmospheric nitrogen into ammonia. Copper and zinc are important in other biological catalysts. Iron, zinc, copper, cobalt, nickel, manganese, and molybdenum are known to be an essential component of enzymes. Vanadium and chromium are also essential for life. Some harmful elements are also present in this block. For example, mercury is toxic and is a threat to the environment.

Recommended topic video on (Transition Elements )


Some Solved Examples

Q.1Transition metals -

1) exhibit diamagnetism

2) undergo inert pair effect

3) do not form alloys

4) show variable oxidation states

Solution:

As we learned,

Transition metals show variable oxidation states, exhibit paramagnetism, and form alloys. The inert pair effect is seen in the heavier elements of the p block and the transition elements do not show this effect.

Hence, the answer is the option (4).

Q.2 Which of the following is not the characteristic of transition metals?

1) They are all metals

2) They show variable oxidation states which always differ by two units

3) They are paramagnetic

4) They easily form complexes

Solution:

As we learned,

Transition elements are all metals and generally show variable oxidation states. Unlike p Block elements which show a difference in oxidation states by two, these elements show a difference in oxidation state of only one unit. This is because of the incomplete filling up of electrons in the d orbitals. Due to their small size and high charge density, they can form complexes

Hence, the answer is the option (2).

Also read :

Conclusion

Transition elements, also known as transition metals, are found in the d-block of the periodic table. They are characterized by their ability to form variable oxidation states and complex ions, and they often exhibit magnetic properties. These elements, such as iron, copper, and nickel, play crucial roles in various industries, and biological, and technological processes due to their unique chemical and physical properties.

Also check-

NCERT Chemistry Notes:

Frequently Asked Questions (FAQs)

Q: How do transition elements participate in redox reactions differently from main group elements?
A:
Transition elements participate in redox reactions differently because:
Q: What is the significance of "crystal field stabilization energy" (CFSE) in transition metal complexes?
A:
Crystal Field Stabilization Energy (CFSE) is significant because:
Q: How does the concept of "hard and soft acids and bases" (HSAB) apply to transition metal complexes?
A:
The HSAB concept is particularly relevant to transition metal complexes:
Q: Why do transition elements often have higher melting and boiling points than main group elements?
A:
Transition elements typically have higher melting and boiling points than main group elements because:
Q: How does the reactivity of transition elements change down a group?
A:
The reactivity of transition elements generally decreases down a group. This is because:
Q: What is the "chelate effect" in transition metal complexes?
A:
The chelate effect refers to the increased stability of complex ions containing chelate ligands compared to similar complexes with monodentate ligands. Chelate ligands are those that can form multiple bonds with a single metal ion. This effect is primarily due to favorable entropy changes and results in more stable complexes, which is important in areas like metal extraction and biochemistry.
Q: How does the atomic radius change across the transition series?
A:
The atomic radius generally decreases across the transition series from left to right. This is due to the increasing effective nuclear charge as protons are added to the nucleus. The added electrons go into the same d-subshell and don't effectively shield the outer electrons from the nuclear charge. However, this decrease is less pronounced than in main group elements due to the d-orbital's poor shielding effect.
Q: Why are many transition elements good conductors of electricity?
A:
Many transition elements are good conductors of electricity because of their metallic bonding structure. The presence of delocalized electrons in the d-orbitals, along with the s-electrons, creates a "sea" of mobile electrons that can easily move through the metal when a potential difference is applied. This high electron mobility results in excellent electrical conductivity.
Q: What is meant by "ligand field theory" in transition metal chemistry?
A:
Ligand field theory is a model used to explain the bonding, orbital arrangement, and electronic properties of transition metal complexes. It describes how the d-orbitals of a transition metal are affected by the electric field produced by surrounding ligands. This theory helps explain the colors, magnetic properties, and reactivity of transition metal complexes.
Q: How do transition elements form interstitial compounds?
A:
Transition elements can form interstitial compounds by incorporating small non-metal atoms (like H, C, N) into the spaces (interstices) between metal atoms in their crystal lattice. These compounds often retain metallic properties but with increased hardness and higher melting points. Examples include tungsten carbide (WC) and titanium nitride (TiN), which are used in cutting tools and coatings.
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