What Are Transition Metals Definition Electronic Configuration Oxidation States and Examples
Transition Metals Definition - The d-block elements are called transition metal. The d-block consists of the elements that are lying in between the s and p blocks. The position of this block is between groups 2 and 13 in the periodic table. It starts from the fourth period onwards. In these elements, the outermost shell contains one or two electrons in their s-orbital but the last electron enters the last but one d subshell (n-1) d. The properties of the elements of this block generally lie between the elements of s block and p block.
Transition Elements List
The transition elements list contain the metals that have incompletely filled d-subshells in their ground state or any one of their oxidation states. Metals included in the transition elements list are:
Scandium (first transition element).
Titanium.
Vanadium.
Chromium.
Manganese.
Iron.
Cobalt.
Nickel.
Copper.
Zinc.
Yttrium.
Zirconium.
Niobium.
Molybdenum.
Technetium.
Ruthenium.
Rhodium.
Palladium.
Silver.
Cadmium.
Lanthanum.
Hafnium.
Tantalum.
Tungsten.
Rhenium.
Osmium.
iridium.
Platinum.
Gold.
Mercury.
Actinium.
Rutherfordium.
Hafnium.
Seaborgium.
Bohrium.
Hassium.
Meitnerium.
Darmstadtium.
Roentgenium.
Copernicium.
First Transition Series
The first transition series consists of elements from scandium, Sc (Z = 21) to zinc, Zn (Z = 30) i.e scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc. The first transition element is scandium, in scandium, the 3d orbital starts filling up and its electronic configuration is [Ar] 4s2 3d1. As we move from scandium onwards, 3d orbitals get filled up more and more till the last element, zinc, in which the 3d orbitals are completely filled [Ar] 4s2 3d10.
Exceptional Electronic Configuration of Chromium (Cr) and Copper (Cu) in Transition Series
The configuration of chromium and copper are anomalous. We know that half-filled and filled electronic configurations have extra stability associated with them. Moreover, the energy difference between 3d and 4s orbitals is not large enough to prevent the electron from entering the 3d orbitals. Thus, to acquire increased stability, one of the 4s electrons goes to nearby 3d orbitals so that the 3d orbital becomes half-filled in the case of chromium and filled in the case of copper respectively. Therefore, the electronic configuration of chromium is [Ar] 3d5 4s1 rather than [Ar] 3d4 4s2 while that of copper is [Ar] 3d10 4s1 instead of [Ar] 3d9 4s2.
Second Transition Series
The 2nd transition series consists of elements from yttrium, Y (Z = 39) to cadmium, Cd (Z = 48), i.e., yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver and cadmium. This series involves the filling of 4d-orbitals.
Third Transition Series
This series consists of elements of lanthanum and from hafnium to mercury i.e., lanthanum, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, and mercury. In between Lanthanum and Hafnium there are fourteen elements called lanthanides which involve the filling of 4f-orbitals and do not belong to this series. The elements of the d-block third series involve the gradual filling of five d-orbitals. It may be noted that, in the second and third transition series, there are many anomalous configurations in comparison to those of the first transition series. These are accredited to the factors like nuclear electron and electron-electron forces.
Fourth Transition Series
It involves the filling of a 6d subshell starting from actinium (Z=89); which has the configuration 6d1 7s2. This fourth transition series in periodic table is incomplete as given in the table below:
General Characteristics of Transition Metals Elements are:
Nearly all the d-block transition elements possess metallic properties such as:
have high tensile strength.
Ductility.
Malleability.
High thermal conductivity.
Electrical conductivity.
Metallic lustre.
Except for mercury which is liquid at room temperature, other transition elements have typical metallic structures.
Transition elements possess a high melting point and high boiling points.
The value of heats of vaporisation is higher than the non-transition elements.
The transition elements have very high densities as compared to the metal of group 1 and 2nd (s block).
The first ionisation energies of d block elements are higher than those of s block elements but are lesser than those of p block elements.
Did You Know?
The fundamental difference in the electronic configuration of transition elements and representative elements is that in the representative elements the valence electrons are present only in the outermost shell. On the other hand, in the transition elements, the valence electrons are present in the outermost shell (ns) as well as the d orbital of the penultimate shell.
The ionization energy of chromium and copper have an exceptionally higher energy than those of their neighbours.
FAQs on Transition Metal Elements Structure Properties and Applications
1. What is a transition metal?
A transition metal is a d-block element that forms at least one ion with a partially filled d-subshell. These elements are located in groups 3–12 of the periodic table and show characteristic properties due to their d-electrons.
- Found in the center of the periodic table (d-block).
- Common examples: Fe, Cu, Ni, Cr, Mn.
- They typically form colored compounds and variable oxidation states.
2. What are the properties of transition metals?
Transition metals are characterized by variable oxidation states, colored compounds, catalytic activity, and complex formation.
- Variable oxidation states (e.g., Fe2+, Fe3+).
- Colored ions and compounds due to d–d electronic transitions.
- Good conductors of heat and electricity.
- High melting and boiling points.
- Catalytic properties, such as Fe in the Haber process.
3. Why do transition metals show variable oxidation states?
Transition metals show variable oxidation states because both their ns and (n−1)d electrons can participate in bonding.
- The energy difference between ns and (n−1)d orbitals is small.
- Electrons can be removed from both subshells.
- Example: Iron forms Fe2+ (loss of 2 electrons) and Fe3+ (loss of 3 electrons).
4. Why are transition metal compounds often colored?
Transition metal compounds are often colored because d–d electronic transitions absorb specific wavelengths of visible light.
- In a complex, d-orbitals split into different energy levels.
- Electrons absorb visible light to move between these split levels.
- The remaining transmitted or reflected light gives the observed color.
5. What is the electronic configuration of transition metals?
The electronic configuration of transition metals generally follows the pattern (n−1)d1–10 ns0–2.
- Electrons fill the (n−1)d subshell after the ns subshell.
- Example: Iron (Fe, Z = 26) is [Ar] 3d6 4s2.
- When forming Fe2+, electrons are removed from 4s first: [Ar] 3d6.
6. What is a complex ion in transition metal chemistry?
A complex ion is a charged species consisting of a central transition metal ion bonded to surrounding ligands by coordinate covalent bonds.
- The central metal ion is usually a transition metal.
- Ligands donate lone pairs (e.g., H2O, NH3, Cl−).
- Example: [Cu(NH3)4]2+.
7. What are some common oxidation states of transition metals?
Common oxidation states of transition metals vary widely, often ranging from +1 to +7.
- Iron: +2, +3
- Copper: +1, +2
- Manganese: +2, +4, +7
- Chromium: +2, +3, +6
8. Are zinc, cadmium, and mercury transition metals?
Zinc, cadmium, and mercury are not considered true transition metals because their common ions have completely filled d-subshells.
- Zn2+: [Ar] 3d10
- Cd2+: [Kr] 4d10
- Hg2+: [Xe] 4f14 5d10
9. Why are transition metals good catalysts?
Transition metals are good catalysts because they can change oxidation states and form intermediate complexes with reactants.
- Variable oxidation states allow electron transfer.
- Surface adsorption weakens reactant bonds.
- Example: Iron catalyzes the Haber process: N2(g) + 3H2(g) → 2NH3(g).
10. What is the difference between transition metals and inner transition metals?
Transition metals are d-block elements (groups 3–12), while inner transition metals are f-block elements (lanthanides and actinides).
- Transition metals: involve filling of d-orbitals.
- Inner transition metals: involve filling of 4f or 5f orbitals.
- Examples: Fe and Cu (transition metals); Ce and U (inner transition metals).
