Transition Elements - Overview, Structure, Properties & Uses

Transition Elements - Definition, Properties, FAQs

Edited By Team Careers360 | Updated on Jul 02, 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.

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Transition Elements-
Some Solved Examples
Conclusion

Transition Elements - Definition, Properties, FAQs

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.

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).

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.

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NCERT Chemistry Notes:

Frequently Asked Questions (FAQs)

1. What do you mean by transition series? Define transition

It is the first transition series which comes under the d block elements from group 3 to 12 of the periodic table.

2. Which elements are known transition metals?

Elements of the periodic table are classified in four categories 1.Main group element 2.transition metals 3.lantanides 4. Actinides, in the other words we can say that the periodic table has 4 blocks namely as s, p, d, and f out of these the d block elements are basically known as the transition metals, transition elements are named transition because their properties lie between s and p block elements of the periodic table.

3. What is The ionization energy of transition elements?

When we go across the metal series from scandium there will be small change in the 1st ionization energy and the 2nd ionization energy, it happens because electrons build up occurs immediately in d-sub-shells due to which the 4s electrons are shields in the nucleus and which minimize the effective nuclear charge from one element to other . There is a rapid increase in 3rd and 4rth ionization energy,because of unpaired electrons of 5d subshell, in singly occupied orbitals.and due to this the inter electron repulsion occurs When the 6th and the further electrons enter in the shell due to which it has to share its orbital which is already occupied, and there is a less requirement of energy to remove electron.

4. what is electronic general electronic configuration of transition elements of transition elements?

The electronic general electronic configuration of transition elements for the first row of lower energy for transition metals is shown below.

Group of the transition metal.

Atomic no.

Symbol

general electronic configuration of transition elements

3d¹s²

3d²s²

3d³s²

3d⁵s¹

3d⁵s²

3d⁶s²

3d⁷s²

3d⁸s²

3d¹⁰4s

3d¹⁰4²

5. What are the chemical properties of transition metals?

The chemical properties of transition metals are as follows

like sodium metal transition metals are less reactive.
Transition metals forms ions with color and also of different charges’
few of them like silver and gold are unreactive
They can also be used as a catalyst in various types of chemical reactions

6. What are transition elements?

Transition elements are metallic elements that have partially filled d-orbitals in their atomic or ionic states. They occupy the d-block of the periodic table, comprising groups 3-12. These elements exhibit variable oxidation states, form colored compounds, and often have catalytic properties.

7. Why are transition elements called "transition" metals?

Transition elements are called "transition" metals because they represent a transition between the highly reactive s-block elements and the less reactive p-block elements. Their properties "transition" from one extreme to another, showing characteristics of both main group elements and inner transition elements.

8. How do the electron configurations of transition elements differ from main group elements?

Transition elements have partially filled d-orbitals in their electron configurations, while main group elements do not. The general electron configuration for transition elements is [Noble gas](n-1)d¹⁻¹⁰ns¹⁻², where n is the highest principal quantum number. This partial filling of d-orbitals leads to many unique properties of transition elements.

9. What is the "d-block contraction" in transition elements?

The d-block contraction refers to the gradual decrease in atomic and ionic radii across a period of transition elements. This occurs because the added electrons in the d-orbitals don't effectively shield the outer electrons from the increasing nuclear charge, causing a stronger attraction between the nucleus and outer electrons.

10. Why do transition elements often form colored compounds?

Transition elements form colored compounds due to d-d transitions. When light hits a transition metal compound, electrons in the partially filled d-orbitals can absorb specific wavelengths of visible light to jump to higher energy levels. The color we see is the complementary color to the wavelength absorbed.

11. How do transition elements exhibit variable oxidation states?

Transition elements can exhibit multiple oxidation states because they have low energy differences between their ns and (n-1)d orbitals. This allows them to lose varying numbers of electrons easily, resulting in different oxidation states. The availability of d-electrons for bonding also contributes to this property.

12. What is the "lanthanide contraction" and how does it affect transition elements?

The lanthanide contraction is the decrease in atomic and ionic radii across the lanthanide series due to poor shielding by 4f electrons. This contraction affects the size of elements in the 6th and 7th periods of the d-block, making them smaller than expected and influencing their chemical properties.

13. Why are many transition elements good catalysts?

Many transition elements are good catalysts because of their ability to change oxidation states easily and form temporary bonds with reactants. Their partially filled d-orbitals allow them to accept or donate electrons, facilitating electron transfer in chemical reactions. They can also adsorb reactants onto their surfaces, bringing them close together to react.

14. How does the melting point trend differ in transition elements compared to main group elements?

Unlike main group elements, transition elements generally have high and variable melting points across a period. This is due to the involvement of d-electrons in metallic bonding, which can create stronger interatomic forces. The melting point often peaks in the middle of the transition series where maximum d-electrons are available for bonding.

15. What is meant by "magnetic properties" of transition elements?

Magnetic properties of transition elements refer to their ability to be attracted to a magnetic field. This is due to the presence of unpaired electrons in their d-orbitals. Transition elements can exhibit paramagnetism (weakly attracted to a magnetic field) or ferromagnetism (strongly attracted and can form permanent magnets), depending on their electron configuration.

16. How do transition elements form complex ions?

Transition elements form complex ions by acting as Lewis acids (electron pair acceptors). Their vacant d-orbitals can accept electron pairs from ligands (Lewis bases), forming coordinate covalent bonds. This ability to form complexes is due to the small size, high charge, and availability of empty orbitals in transition metal ions.

17. What is the "spectrochemical series" in transition metal complexes?

The spectrochemical series is an ordering of ligands based on their ability to cause d-orbital splitting in transition metal complexes. It ranges from weak-field ligands (small splitting) to strong-field ligands (large splitting). This splitting affects the color, magnetic properties, and stability of the complexes.

18. How does the reactivity of transition elements compare to that of alkali metals?

Transition elements are generally less reactive than alkali metals. While alkali metals readily lose their single valence electron, transition elements have stronger metallic bonds due to d-electron involvement. This makes transition elements harder, less volatile, and less reactive with water and air compared to alkali metals.

19. Why do many transition elements have high densities?

Many transition elements have high densities due to their small atomic radii and the efficient packing of atoms in their crystal structures. The involvement of d-electrons in metallic bonding leads to stronger interatomic forces, resulting in a more compact structure and higher density compared to main group elements.

20. What is the "Irving-Williams series" and why is it important?

The Irving-Williams series is an empirical ordering of the stability of high-spin complexes formed by divalent ions of the first-row transition metals. The order is Mn²⁺ < Fe²⁺ < Co²⁺ < Ni²⁺ < Cu²⁺ > Zn²⁺. It's important because it helps predict and explain the relative stability of metal complexes, which is crucial in fields like coordination chemistry and biochemistry.

21. How do transition elements differ in their ability to form alloys?

Transition elements are excellent at forming alloys due to their similar atomic sizes and ability to adopt different oxidation states. They can form substitutional alloys with each other, where atoms of one element replace those of another in the crystal lattice. This property is widely used in creating materials with enhanced strength, corrosion resistance, and other desirable properties.

22. What is the "18-electron rule" in transition metal complexes?

The 18-electron rule states that stable transition metal complexes often have a total of 18 valence electrons around the central metal atom. This includes the metal's own valence electrons and those donated by ligands. The rule helps predict the stability and geometry of complexes, although there are many exceptions, especially for early transition metals.

23. How does the electronegativity of transition elements change across a period?

The electronegativity of transition elements generally increases from left to right across a period. This trend is due to the increasing effective nuclear charge as protons are added to the nucleus, while electrons are added to the same principal energy level. However, the change is less pronounced than in main group elements due to the shielding effect of d-electrons.

24. Why do some transition elements form colored solutions in water?

Some transition elements form colored solutions in water because their hydrated ions have partially filled d-orbitals. When light interacts with these ions, d-d transitions occur, causing the absorption of specific wavelengths of visible light. The observed color is complementary to the absorbed color. For example, copper(II) ions produce a blue solution because they absorb orange light.

25. What is the difference between "high-spin" and "low-spin" complexes in transition elements?

High-spin and low-spin complexes refer to different electron configurations in transition metal complexes. In high-spin complexes, electrons occupy orbitals singly before pairing, maximizing the number of unpaired electrons. In low-spin complexes, electrons pair in lower energy orbitals before occupying higher energy orbitals. The type of complex formed depends on the strength of the ligand field and affects magnetic and spectral properties.

26. How do transition elements contribute to biological processes?

Transition elements play crucial roles in biological processes, often as part of metalloenzymes or cofactors. For example, iron in hemoglobin transports oxygen, copper in cytochrome c oxidase is involved in electron transport, and zinc in carbonic anhydrase catalyzes the conversion of carbon dioxide to bicarbonate. Their ability to change oxidation states and form complexes makes them essential for many biochemical reactions.

27. What is the "chelate effect" in transition metal complexes?

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.

28. How does the atomic radius change across the transition series?

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.

29. Why are many transition elements good conductors of electricity?

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.

30. What is meant by "ligand field theory" in transition metal chemistry?

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.

31. How do transition elements form interstitial compounds?

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.

32. What is the significance of the "spectrochemical series" in transition metal complexes?

The spectrochemical series is significant because it helps predict and explain the properties of transition metal complexes. It orders ligands based on their ability to cause d-orbital splitting, which affects:

33. How does the first ionization energy trend differ in transition elements compared to main group elements?

The first ionization energy trend in transition elements is less regular than in main group elements. While it generally increases across a period, there are often small fluctuations. This is because removing an electron from a d-orbital (which is being filled) has less effect on the atom's stability than removing an s or p electron. The trend is also influenced by the stability of half-filled (d⁵) and fully-filled (d¹⁰) d-subshells.

34. Why do transition elements often form coordination compounds?

Transition elements often form coordination compounds because:

35. How does the reactivity of transition elements change down a group?

The reactivity of transition elements generally decreases down a group. This is because:

36. What is the "trans effect" in transition metal complexes?

The trans effect is a kinetic phenomenon in which certain ligands in a square planar or octahedral complex influence the rate of substitution of the ligand opposite (trans) to them. Ligands with a strong trans effect weaken the bond between the metal and the ligand trans to them, making that ligand more easily replaced. This effect is important in understanding reaction mechanisms and in the synthesis of specific isomers of coordination compounds.

37. How do transition elements contribute to catalytic converters in vehicles?

Transition elements, particularly platinum, palladium, and rhodium, are crucial components of catalytic converters because:

38. What is meant by "Jahn-Teller distortion" in transition metal complexes?

Jahn-Teller distortion is a geometric distortion of non-linear molecular systems that reduces its symmetry and energy. In transition metal complexes, it occurs when the electronic ground state is degenerate. The distortion removes this degeneracy, lowering the overall energy of the complex. This effect is most commonly observed in octahedral complexes of d⁹ ions (like Cu²⁺) and high-spin d⁴ ions, where it leads to an elongation of the octahedron along one axis.

39. How does the presence of transition elements affect the properties of alloys?

Transition elements significantly influence alloy properties:

40. Why do transition elements often have higher melting and boiling points than main group elements?

Transition elements typically have higher melting and boiling points than main group elements because:

41. How does the concept of "hard and soft acids and bases" (HSAB) apply to transition metal complexes?

The HSAB concept is particularly relevant to transition metal complexes:

42. What is the significance of "crystal field stabilization energy" (CFSE) in transition metal complexes?

Crystal Field Stabilization Energy (CFSE) is significant because:

43. How do transition elements participate in redox reactions differently from main group elements?

Transition elements participate in redox reactions differently because: