Transition Metal Chemistry (3d, 4d, And 5d Block Elements)

The d block elements are a group of elements located in the middle of the periodic table. They are also known as transition metals because they form a transition series between the s-block and p-block elements.

Table of Contents

Transition Metals / d block Elements

The d-block elements occupy the center of the periodic table, extending from group 3 to group 12. Transition metals are characterized by their partially filled d orbitals. This in a way contributes to their significance and wide range of applications. Some notable examples include:

The widely use of transition metals and their compounds as catalysts in industrial processes. For instance, iron is used in the production of steel, which is a vital material in construction. Platinum and palladium are used as catalysts in the production of chemicals, while nickel is used in the production of stainless steel.

Many transition metals are used in electronics and technology. Copper is commonly used in electrical wiring due to its excellent electrical conductivity. Transition metals like gold and silver are used in various electronic components and connectors. You also find these d block elements batteries, magnetic materials, and superconductors.

In biological systems these d block elements play crucial roles. Iron is an essential component of hemoglobin, which carries oxygen in human blood. Platinum-based compounds, such as cisplatin, are widely used in chemotherapy to treat cancer. Other transition metals like zinc, copper, and manganese are necessary for various enzymatic reactions in the body.

Transition metals are used in environmental applications, such as water purification and air pollution control. Transition metal catalysts are employed in catalytic converters to reduce harmful emissions from vehicles. Also, transition metal oxides, such as titanium dioxide, are used in photocatalytic reactions for water treatment and air purification.

See: The Complete Periodic Table

General Trends in the Periodic Table for d block Elements

There are several general trends observed in the periodic table for d-block metals:

Atomic Size

Across a period (from left to right), the atomic size of transition metals generally decreases. This is due to the increasing nuclear charge, which attracts the electrons more strongly, leading to a contraction in atomic size.

Ionization Energy

Transition metals generally have high ionization energies, meaning that it requires a significant amount of energy to remove an electron from their outermost shell.

Electronegativity

Transition metals have relatively low electronegativities, which means they have a tendency to lose electrons rather than gain them when forming compounds.

Metallic Character

Transition metals are known for their high metallic character. They have a shiny appearance, good thermal and electrical conductivity, and are malleable and ductile.

General Characteristics of d block Elements

Metallic Properties

d-block elements are known for their metallic properties. They possess high thermal and electrical conductivity, malleability, and ductility unlike the s block metals. These properties arise from the presence of delocalized electrons in their metallic bonding. The partially filled d orbitals contribute to the conductivity of transition metals. They allow the movement of electrons through the metal lattice, enabling the transfer of heat or electricity. The ability to be shaped or drawn into wires (malleability and ductility) is due to the relatively mobile nature of the d electrons.

High Melting and Boiling Points

d block elements generally have high melting and boiling points compared to other elements on the periodic table. This characteristic is due to the strong metallic bonding between the positively charged metal ions and the delocalized electrons in their structures. The presence of partially filled d orbitals contributes to the strength of metallic bonding, resulting in higher melting and boiling points.

See More About: Metallic Bonding in Compounds

Variable Oxidation States

One of the prominent characteristics of d-block elements is their ability to exhibit variable oxidation states. This arises from the availability of unpaired electrons in their d orbitals. The d orbitals have a range of energies, allowing these elements to easily lose or gain electrons and form compounds with different oxidation states. The ability to display multiple oxidation states makes d-block elements highly versatile in chemical reactions and enables them to form a wide variety of compounds.

Magnetic Properties

Transition metals often exhibit magnetic properties. This behavior arises from the presence of unpaired electrons in their partially filled d orbitals. These unpaired electrons can align their spins in the presence of an external magnetic field, resulting in a net magnetic moment. This property makes transition metals susceptible to magnetic attraction and allows them to be used in applications such as magnets, magnetic storage devices, and magnetic resonance imaging (MRI) machines.

Formation of Complex ions

Transition metals have a strong tendency to form complex ions by coordinating with ligands. Ligands are molecules or ions that donate electron pairs to the metal ion, forming coordinate bonds. The ability of transition metals to form complex ions arises from their small atomic sizes and the availability of empty d orbitals for accepting electron pairs. These complex ions exhibit unique properties and play essential roles in various biological and chemical processes, such as enzymatic reactions and catalysis.

See More: Metal Complexes of First Row Transition Metals

Formation of Colored Compounds

Transition metals are renowned for their capability to form colorful compounds. This phenomenon is a result of the partially filled d orbitals. When transition metal ions form compounds, they interact with ligands, which are molecules or ions that bond to the metal ion by donating electron pairs. The d orbitals split into different energy levels in the presence of ligands, creating a range of energy gaps. When white light falls on these compounds, some colors are absorbed while others are reflected or transmitted. The absorbed colors give rise to the observed color of the compound. Therefore, the formation of colored compounds is due to the interaction between d orbitals and ligands, which causes the absorption and reflection of specific wavelengths of light.

Catalytic Activity

Transition metals exhibit exceptional catalytic activity. This characteristic stems from their ability to undergo changes in oxidation states easily. The presence of variable oxidation states allows them to participate in redox reactions by accepting or donating electrons. Transition metals can act as catalysts by providing an alternative reaction pathway with lower activation energy. They facilitate chemical reactions without being consumed in the process. This catalytic activity is utilized in various industrial processes, such as the Haber process for ammonia production or the oxidation of hydrocarbons in petroleum refining.

Electronic Configuration of 3d, 4d, and 5d Block Elements

The d block has three rows. Each of the rows is made up of ten elements. The first, second and third row elements which are called the 3d, 4d, and 5d block elements have partially filled d orbitals in their electron configurations, contributing to their distinctive characteristics and chemistry have some similarities and differences.

3d	4d	5d
Scandium (Sc) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹	Yttrium (Y) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹	Lanthanum (La) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 5d¹
Titanium (Ti) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d²	Zirconium (Zr) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d²	Hafnium (Hf) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d²
Vanadium (V) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d³	Niobium (Nb) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d⁴	Tantalum (Ta) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d³
Chromium (Cr) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵	Molybdenum (Mo) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹ 4d⁵	Tungsten (W) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d⁴
Manganese (Mn) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁵	Technetium (Tc) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d⁵	Rhenium (Re) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d⁵
Iron (Fe) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶	Ruthenium (Ru) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹ 4d⁷	Osmium (Os) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d⁶
Cobalt (Co) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁷	Rhodium (Rh) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹ 4d⁸	Iridium (Ir) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d⁷
Nickel (Ni) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁸	Palladium (Pd) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s⁰ 4d¹⁰	Platinum (Pt) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d⁹
Copper (Cu) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d¹⁰	Silver (Ag) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s⁰ 4d¹⁰ 5p⁶	Gold (Au) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰
Zinc (Zn) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰	Cadmium (Cd) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰	Mercury (Hg) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰

General Similarities Between 3d, 4d, and 5d Block Elements

The 3d, 4d, and 5d block elements share several general characteristics typical of transition metals which was earlier mentioned. For emphasis sake, these include the ability to exhibit variable oxidation states, the formation of colored compounds, the formation of coordination compounds, catalytic activity, and metallic properties such as high thermal and electrical conductivity. These shared characteristics arise from the presence of partially filled d orbitals, which allow for diverse bonding and reactivity.

General Differences Between 3d, 4d, and 5d block Elements

Position in the Periodic Table

The 3d block elements are found in the fourth period of the periodic table, while the 4d and 5d block elements are located in the fifth and sixth periods, respectively. The position of these elements determines their atomic numbers, electron configurations, and chemical behavior.

Energy Levels and Sizes

As we move from 3d to 5d, there is an increase in energy levels of the d orbitals. The 5d orbitals are further from the nucleus compared to the 4d and 3d orbitals, resulting in larger atomic sizes for the 5d block elements. This difference in energy levels and atomic sizes influences their chemical properties and reactivity.

Stability of Oxidation States

The 3d block elements exhibit a wider range of oxidation states compared to the 4d and 5d block elements. This is due to the presence of fewer shielding electrons in the 3d orbitals, allowing for stronger interactions with ligands and more variability in oxidation states. The 4d and 5d block elements tend to display fewer oxidation states overall due to increased electron shielding.

Occurrences, Extractions, and Physical Properties

First Row Transition Metals (3d Elements)

Generally, as we move from 3d to 5d, there is a decrease in reactivity. The larger atomic size and increased electron shielding in the 4d and 5d block elements reduce their reactivity compared to the 3d block elements. However, this is a general trend and may have exceptions within specific elements or compounds.

Scandium (Sc)

Occurrence: Scandium occurs in small amounts in minerals such as thortveitite, euxenite, and wolframite.

Extraction: Scandium is primarily extracted as a byproduct during the processing of uranium and tungsten ores. Solvent extraction and ion exchange methods are used to isolate and purify scandium.

Physical Properties: Scandium is a silvery-white metal with a relatively low density and a high melting point. It is corrosion-resistant and exhibits good electrical conductivity.

Titanium (Ti)

Occurrence: Titanium is the 9th most abundant element in the Earth’s crust and is found in minerals such as rutile (TiO₂) and ilmenite (FeTiO₃).

Extraction: Titanium is obtained from its ores through a process known as the Kroll process. This involves reducing titanium tetrachloride (TiCl₄) with magnesium to produce titanium sponge, which is further processed to obtain pure titanium.

2 Mg + TiCl₄ -> 2 MgCl₂ + Ti

Physical Properties: Titanium is a strong, lightweight metal with a silver-gray color. It has a high melting point, excellent corrosion resistance, and is biocompatible. Titanium finds applications in aerospace, medical implants, and the chemical industry.

Vanadium (V)

Occurrence: Vanadium is primarily found in minerals such as vanadinite (Pb₅(VO₄)₃Cl) and magnetite (Fe₃O₄). It also occurs in fossil fuels and some types of crude oil.

Extraction: Vanadium is extracted from its ores through various processes, including roasting, leaching, and solvent extraction. The extracted vanadium is then further purified using precipitation or ion exchange methods.

Roasting: V₂O₅(s) + O₂(g) → 2 V₂O₅(g)

Leaching: V₂O₅(g) + 2 Na₂CO₃(aq) + H₂O(l) → 2 NaVO₃(aq) + 2 CO₂(g)

Solvent Extraction: NaVO₃(aq) + Organic solvent → Vanadium-containing organic complex

Precipitation (Purification):

Vanadium-containing organic complex + 2 NH₄Cl(aq) → (NH₄)₃VO₃(s) + NH₄VO₃(aq) + HCl(aq)

Ion Exchange (Purification): NH₄VO₃(aq) + Ion exchange resin → Pure vanadium compounds + NH₄Cl(aq)

Physical Properties: Vanadium is a hard, silvery-gray metal with a high melting point. It exhibits good corrosion resistance and is known for its high strength-to-weight ratio. Vanadium is used in the production of steel, as a catalyst, and in energy storage systems.

Chromium (Cr)

Occurrence: Chromium is mainly found in the mineral chromite (FeCr₂O₄), which is widely distributed around the world.

Extraction: Chromium is extracted from chromite ore through a two-step process. First, the ore is concentrated through gravity separation or magnetic separation methods. Then, it is subjected to a smelting process, where chromite is mixed with coke and lime and reduced in an electric arc furnace.

Concentration (Gravity Separation or Magnetic Separation):

Chromite ore (FeCr₂O₄) + Inert matrix → Concentrated chromite ore

Smelting: 2 FeCr₂O₄(s) + 8 C(s) + 4 CaO(s) → 4 Cr(s) + 8 Fe(s) + 4 CO(g) + 4 CaSiO₃(s)

Physical Properties: Chromium is a hard, silvery-gray lustrous metal with a high melting point. It exhibits excellent corrosion resistance and can form a thin, self-healing oxide layer on its surface. Chromium finds applications in stainless steel production, decorative finishes, and as a component in alloys.

Manganese (Mn)

Occurrence: Manganese is widely distributed in the Earth’s crust and is primarily found in minerals such as pyrolusite (MnO₂), rhodochrosite (MnCO₃), and braunite (Mn²⁺Mn³⁺6SiO₁₂).

Extraction: Manganese is extracted from its ores through a pyrometallurgical process called smelting. The ore is first roasted to convert manganese dioxide (MnO₂) into manganese oxide (MnO), which is then reduced with carbon to obtain manganese metal.

Roasting: 2 MnO₂(s) → 2 MnO(s) + O₂(g)

Reduction: MnO(s) + C(s) → Mn(s) + CO(g)

Physical Properties: Manganese is a gray-white, hard metal with a high melting point. It is brittle in its pure form but becomes more ductile when alloyed with other elements. Manganese is used in steel production, batteries, and as a catalyst.

Iron (Fe)

Occurrence: Iron is one of the most abundant elements on Earth and is primarily found in minerals such as hematite (Fe₂O₃), magnetite (Fe₃O₄), and siderite (FeCO₃).

Extraction: Iron is extracted from iron ore through a process called smelting. The ore is first crushed and then heated with coke (carbon) in a blast furnace, resulting in the reduction of iron oxide to metallic iron.

Crushing: Iron ore (Fe₂O₃) + Coke (C) → Crushed iron ore + Carbon monoxide (CO)

Reduction in the Blast Furnace: 3 Fe₂O₃(s) + 3 CO(g) → 2 Fe₃O₄(s) + 3 CO₂(g)

Fe₃O₄(s) + 4 CO(g) → 3 Fe(s) + 4 CO₂(g)

Physical Properties: Iron is a silver-gray, lustrous metal with a high melting point. It is malleable, ductile, and possesses good tensile strength. Iron is widely used in construction, manufacturing, and as a core component in steel production.

Cobalt (Co)

Occurrence: Cobalt is mostly found in association with nickel ores, such as pentlandite [(Fe,Ni)₉S₈] and pyrrhotite (Fe₁-xS).

Extraction: Cobalt is typically extracted as a byproduct of nickel or copper mining and refining processes. The extraction methods involve various steps, including crushing, roasting, leaching, and precipitation.

Physical Properties: Cobalt is a hard, lustrous metal with a bluish-gray appearance. It has a high melting point and retains its magnetic properties at elevated temperatures. Cobalt finds applications in rechargeable batteries, superalloys, and magnetic materials.

Nickel (Ni)

Occurrence: Nickel is primarily found in sulfide ores, such as pentlandite [(Fe,Ni)₉S₈] and pyrrhotite (Fe1-xS), as well as in laterite deposits.

Extraction: Nickel is extracted from its ores through various methods, including flotation, smelting, and refining. The extracted nickel is then further processed to obtain pure nickel metal.

Physical Properties: Nickel is a silver-white metal with a high melting point. It is malleable, ductile, and exhibits good corrosion resistance. Nickel is widely used in the production of stainless steel, batteries, and as a catalyst.

Copper (Cu)

Occurrence: Copper occurs in various minerals, including chalcopyrite (CuFeS₂), bornite (Cu₅FeS₄), and malachite (Cu₂CO₃(OH)₂). It can also be found in native form.

Extraction: Copper is extracted from sulfide ores through a process called smelting. The ore is first concentrated by froth flotation, and then roasted to convert copper sulfides into copper oxides. The resulting oxides are then reduced to obtain metallic copper.

Physical Properties: Copper is a reddish-brown metal with excellent electrical and thermal conductivity. It is malleable, ductile, and has a relatively high melting point. Copper is widely used in electrical wiring, plumbing, and as a conductor of heat and electricity.

Zinc (Zn)

Occurrence: Zinc is primarily found in the mineral sphalerite (ZnS) and is also present in some other zinc-containing ores such as smithsonite (ZnCO₃) and hemimorphite (Zn₄Si₂O₇(OH)₂·H₂O).

Extraction: Zinc is commonly extracted from its ores through a process called roasting and reduction. The ore is first roasted to convert zinc sulfide (ZnS) into zinc oxide (ZnO), which is then reduced with carbon or carbon monoxide to obtain metallic zinc.

Physical Properties: Zinc is a bluish-white metal with a low melting point and good ductility. It is relatively brittle at room temperature but becomes malleable when heated. Zinc is widely used in galvanizing steel, as a corrosion inhibitor, and in the production of alloys.

Second Row Transition Metals (4d Elements)

Yttrium (Y)

Occurrence: Yttrium is found in rare earth minerals such as monazite and xenotime, as well as in some other minerals.

Extraction: Yttrium is extracted from its ores through a process that involves leaching the ores with acid, followed by solvent extraction or precipitation to obtain yttrium compounds.

Physical Properties: Yttrium is a silvery-white, lustrous metal with a hexagonal close-packed crystal structure. It has a melting point of 1526°C and a density of 4.47 g/cm³.

Zirconium (Zr)

Occurrence: Zirconium is primarily found in the mineral zircon (ZrSiO₄) and other zirconium silicate minerals.

Extraction: Zirconium is extracted from zirconium ores through a series of chemical and physical processes, including grinding, digestion, and chemical treatment, to obtain zirconium compounds.

Physical Properties: Zirconium is a grayish-white, lustrous metal with a body-centered cubic crystal structure. It has a melting point of 1852°C and a density of 6.51 g/cm³.

Niobium (Nb)

Occurrence: Niobium is primarily found in the minerals pyrochlore and columbite, as well as in some other tantalum-containing minerals.

Extraction: Niobium is extracted from its ores through a series of processes that involve grinding, digestion, and chemical treatment to obtain niobium compounds.

Physical Properties: Niobium is a gray, lustrous metal with a body-centered cubic crystal structure. It has a melting point of 2468°C and a density of 8.57 g/cm³.

Molybdenum (Mo)

Occurrence: Molybdenum is found in various ores, including molybdenite (MoS₂) and wulfenite (PbMoO₄).

Extraction: Molybdenum is extracted from its ores through a process that involves crushing, grinding, and flotation to separate molybdenite from other minerals.

Physical Properties: Molybdenum is a silvery-white, lustrous metal with a body-centered cubic crystal structure. It has a melting point of 2623°C and a density of 10.28 g/cm³.

Technetium (Tc)

Occurrence: Technetium is a radioactive element and is not naturally abundant on Earth. It is primarily produced artificially through nuclear reactions.

Extraction: Technetium is not extracted from ores but rather synthesized in nuclear reactors by bombarding certain target materials with neutrons.

Physical Properties: Technetium is a silvery-gray, radioactive metal. It has a melting point of 2157°C and a density of 11.5 g/cm³.

Ruthenium (Ru)

Occurrence: Ruthenium is a rare element and is usually found as a minor component in ores containing platinum group metals.

Extraction: Ruthenium is obtained as a byproduct of the extraction and refining of other platinum group metals.

Physical Properties: Ruthenium is a silvery-white, hard metal with a hexagonal close-packed crystal structure. It has a melting point of 2334°C and a density of 12.41 g/cm³.

Rhodium (Rh)

Occurrence: Rhodium is found in small amounts in platinum ores, nickel ores, and copper-nickel ores.

Extraction: Rhodium is obtained as a byproduct of the extraction and refining of other platinum group metals.

Physical Properties: Rhodium is a silver-white, hard metal with a face-centered cubic crystal structure. It has a melting point of 1966°C and a density of 12.41 g/cm³.

Palladium (Pd)

Occurrence: Palladium is found in various ores, including nickel-copper sulfide ores and platinum group metal ores.

Extraction: Palladium is obtained as a byproduct of the extraction and refining of other platinum group metals.

Physical Properties: Palladium is a silver-white, ductile metal with a face-centered cubic crystal structure. It has a melting point of 1554°C and a density of 12.02 g/cm³.

Silver (Ag)

Occurrence: Silver is found in various ores, including silver sulfide ores (such as argentite) and silver-bearing lead or copper ores.

Extraction: Silver is extracted from its ores through a process that involves crushing, grinding, and flotation, followed by smelting to obtain silver metal.

Physical Properties: Silver is a shiny, white metal with a face-centered cubic crystal structure. It has a melting point of 961.8°C and a density of 10.49 g/cm³.

Cadmium (Cd)

Occurrence: Cadmium is primarily found in zinc ores, such as sphalerite (ZnS).

Extraction: Cadmium is obtained as a byproduct of the extraction and refining of zinc metal.

Physical Properties: Cadmium is a bluish-white, soft metal with a hexagonal close-packed crystal structure. It has a melting point of 321.1°C and a density of 8.65 g/cm³.

Third Row Transition Metals (5d Elements)

Lanthanum (La)

Occurrence: Lanthanum is found in a variety of minerals such as monazite [(Ce,La,Th,Nd,Y)PO₄] and bastnäsite [(Ce,La,Nd)(CO₃)F]. It is also found in small quantities in some rare-earth ores.

Extraction: Lanthanum is typically extracted from the minerals through a process called solvent extraction, which involves separating lanthanum from other rare-earth elements.

Physical Properties: Lanthanum is a silvery-white, malleable, and ductile metal. It has a melting point of 920°C and a density of 6.15 g/cm³.

Hafnium (Hf)

Occurrence: Hafnium is primarily found in zirconium minerals, such as zircon (ZrSiO₄) and baddeleyite (ZrO₂).

Extraction: Hafnium is extracted from zirconium minerals through a series of chemical processes, including leaching, precipitation, and purification steps.

Physical Properties: Hafnium is a lustrous, silvery metal. It has a high melting point of 2,233°C and a density of 13.3 g/cm³.

Tantalum (Ta)

Occurrence: Tantalum is found in minerals such as columbite [(Fe,Mn)(Nb,Ta)₂O₆] and tantalite [(Fe,Mn)(Ta,Nb)₂O₆]. It is also present in tin ores.

Extraction: Tantalum is extracted from its ores through a combination of crushing, milling, and chemical separation techniques.

Physical Properties: Tantalum is a dense, blue-gray metal. It has a high melting point of 3,017°C and a density of 16.6 g/cm³.

Tungsten (W)

Occurrence: Tungsten is primarily found in the minerals wolframite [(Fe,Mn)WO₄] and scheelite (CaWO₄). It is also present in some tin ores.

Extraction: Tungsten is extracted from its ores through a series of chemical processes, including gravity separation, flotation, and roasting.

Physical Properties: Tungsten is a hard, brittle, and steel-gray metal. It has an extremely high melting point of 3,422°C and a density of 19.3 g/cm³.

Rhenium (Re)

Occurrence: Rhenium is a rare element and is usually found in small quantities in molybdenite (MoS₂) and copper porphyry deposits.

Extraction: Rhenium is obtained as a byproduct of copper and molybdenum mining. It is separated from other metals through a series of chemical processes.

Physical Properties: Rhenium is a silvery-white, heavy metal. It has a high melting point of 3,180°C and a density of 21.0 g/cm³.

Osmium (Os)

Occurrence: Osmium is found in platinum ores, mainly as an alloy with platinum and other platinum group metals.

Extraction: Osmium is extracted as a byproduct of platinum refining. The extraction involves various chemical processes to separate osmium from other metals.

Physical Properties: Osmium is a hard, brittle, bluish-white metal. It has a very high melting point of 3,033°C and a density of 22.6 g/cm³.

Iridium (Ir)

Occurrence: Iridium is primarily found in platinum ores, such as sperrylite (PtAs₂) and cooperite [(Pt,Pd,Ni)S].

Extraction: Iridium is obtained as a byproduct of platinum refining. The extraction involves various chemical processes to separate iridium from other platinum group metals.

Physical Properties: Iridium is a dense, corrosion-resistant, silvery-white metal. It has an extremely high melting point of 2,447°C and a density of 22.4 g/cm³.

Platinum (Pt)

Occurrence: Platinum is found in various minerals, mainly in the form of alloys with other platinum group metals. It is also found in alluvial deposits.

Extraction: Platinum is extracted from its ores through a process called refining, which involves crushing, grinding, and chemical separation methods.

Physical Properties: Platinum is a dense, malleable, and highly ductile metal. It has a melting point of 1,768°C and a density of 21.4 g/cm³.

Gold (Au)

Occurrence: Gold is found in its native form as nuggets or grains in rocks, alluvial deposits, and veins.

Extraction: Gold is extracted from its ores through various methods, including crushing, grinding, gravity separation, and cyanidation.

Physical Properties: Gold is a dense, soft, yellow metal. It has a melting point of 1,064°C and a density of 19.3 g/cm³.

Mercury (Hg)

Occurrence: Mercury is found in cinnabar (HgS) ores and is often associated with other metal ores, such as zinc and lead.

Extraction: Mercury is obtained by heating the cinnabar ore, which converts mercury sulfide into elemental mercury vapor. The vapor is then condensed and collected.

Physical Properties: Mercury is the only metal that exists in liquid form at room temperature. It is silvery-white and has a density of 13.5 g/cm³.

Oxidation States of the d block Elements

3d	4d	5d
Scandium (Sc) 21, [Sc³⁺ (example: ScCl₃)]	Yttrium (Y) 39, [Y³⁺ (example: Y₂O₃)]	Lanthanum (La) 57, [La³⁺ (example: La₂(SO₄)₃)]
Titanium (Ti) 22, [Ti²⁺ (example: TiCl₂)], [Ti³⁺ (example: TiI₃)]	Zirconium (Zr) 40, [Zr⁴⁺ (example: ZrO₂)]	Hafnium (Hf) 72, [Hf⁴⁺ (example: HfF₄)]
Vanadium (V) 23, [V²⁺ (example: VCl₂)], [V³⁺ (example: VOCl₃)], [V⁵⁺ (example: V₂O₅)]	Niobium (Nb) 41, [Nb³⁺ (example: NbCl₃)], [Nb⁵⁺ (example: Nb₂O₅)]	Tantalum (Ta) 73, [Ta⁵⁺ (example: TaF₅)]
Chromium (Cr) 24, [Cr²⁺ (example: CrCl₂)], [Cr³⁺ (example: CrCl₃)], [Cr⁶⁺ (example: CrO₃)]	Molybdenum (Mo) 42, [Mo³⁺ (example: MoCl₃)], [Mo⁶⁺ (example: MoO₃)]	Tungsten (W) 74, [W⁴⁺ (example: WF₄)], [W⁶⁺ (example: WO₃)]
Manganese (Mn) 25, [Mn²⁺ (example: MnCl₂)], [Mn³⁺ (example: MnCl₃)], [Mn⁷⁺ (example: Mn₂O₇)]	Technetium (Tc) 43, [Tc⁷⁺ (example: TcO₄^–)]	Rhenium (Re) 75, [Re⁴⁺ (example: ReCl₄)], [Re⁷⁺ (example: ReO₄^–)]
Iron (Fe) 26, [Fe²⁺ (example: FeCl₂)], [Fe³⁺ (example: FeCl₃)]	Ruthenium (Ru) 44, [Ru³⁺ (example: RuCl₃)], [Ru⁴⁺ (example: RuO₂)], [Ru⁶⁺ (example: RuO₄)]	Osmium (Os) 76, [Os⁴⁺ (example: OsCl₄)], [Os⁸⁺ (example: OsO₄)]
Cobalt (Co) 27, [Co²⁺ (example: CoCl₂)], [Co³⁺ (example: CoCl₃)]	Rhodium (Rh) 45, [Rh³⁺ (example: RhCl₃)]	Iridium (Ir) 77, [Ir³⁺ (example: IrCl₃)], [Ir⁴⁺ (example: IrO₂)], [Ir⁹⁺ (example: IrO₄)]
Nickel (Ni) 28, [Ni²⁺ (example: NiCl₂)], [Ni³⁺ (example: NiCl₃)]	Palladium (Pd) 46, [Pd²⁺ (example: PdCl₂)], [Pd⁴⁺ (example: PdO₂)], [Pd⁶⁺ (example: PdO₃)]	Platinum (Pt) 78, [Pt²⁺ (example: PtCl₂)], [Pt⁴⁺ (example: PtO₂)], [Pt⁶⁺ (example: PtO₃)]
Copper (Cu) 29, [Cu¹⁺ (example: CuCl)], [Cu²⁺ (example: CuCl₂)]	Silver (Ag) 47, [Ag¹⁺ (example: AgCl)]	Gold (Au) 79, [Au¹⁺ (example: AuCl)]
Zinc (Zn) 30, [Zn²⁺ (example: ZnCl₂)]	Cadmium (Cd) 48, [Cd²⁺ (example: CdCl₂)]	Mercury (Hg) 80, [Hg²⁺ (example: HgCl₂)]

Transition Metals and Alloy Formation

Alloy formation involves the mixing of two or more metallic elements to create a material with enhanced properties compared to the individual components. Though the formation of alloys is not an inherent characteristic of d-block elements specifically. Alloys can be formed with elements from different blocks of the periodic table, including the s-block, p-block, and d-block elements. The chemistry behind alloy formation is complex and depends on various factors such as atomic size, electronegativity, crystal structure, and the electronic configuration of the elements involved.

Transition metals have incompletely filled d orbitals, which allow for the formation of multiple oxidation states. This flexibility in oxidation states enables the transition metals to participate in various chemical reactions, including alloy formation.

One of the key factors in alloy formation is the solid solution, where atoms of different elements occupy the same crystal lattice. In a solid solution, the atoms of the alloying elements are randomly distributed throughout the crystal lattice, resulting in a homogeneous material. The d-block elements, with their similar atomic sizes and electronegativities, can easily substitute or intermix within the crystal lattice, promoting the formation of solid solutions.

Moreover, the d-block elements exhibit metallic bonding, which is characterized by the delocalization of electrons across the lattice structure. This electron delocalization gives rise to properties such as high electrical and thermal conductivity, malleability, and ductility. When different d-block elements are combined in an alloy, their electronic configurations and metallic bonding interactions can result in synergistic effects, leading to improved mechanical, thermal, and chemical properties of the alloy.

For example, one of the well-known alloy systems is steel, which is primarily composed of iron (Fe) with small amounts of carbon (C) and other elements. The addition of carbon to iron forms an interstitial solid solution, strengthening the material and giving it improved hardness and wear resistance. Similarly, other d-block elements like chromium (Cr), nickel (Ni), and manganese (Mn) can be added to steel to enhance corrosion resistance, strength, or heat resistance, depending on the specific requirements.

Some other examples are bronze, an alloy which composed primarily of copper (Cu) and tin (Sn) and brass, an alloy composed of copper (Cu) and zinc (Zn).

Alloys have shown to have enhanced mechanical strength, heat and corrosion resistance with versatile and wide range of applications.

Chemical Reactions of d Block Elements

There are ten triads in the d block, each having 3d, 4d and 5d members. Elements of the same triad react similarly and have some reactions that are particular to individual elements in the triad. Let us explore these reactivity:

First Triad: Sc, Y & La

Scandium (Sc)

Reaction with hydrochloric acid:

– Scandium reacts with hydrochloric acid to form scandium chloride and hydrogen gas:

– 2Sc + 6HCl → 2ScCl₃ + 3H₂

Reaction with sulfuric acid:

– Scandium reacts with sulfuric acid to form scandium sulfate and hydrogen gas:

– 2Sc + 3H₂SO₄ → Sc₂(SO₄)₃ + 3H₂

Reaction with oxygen:

– Scandium reacts with oxygen in the air to form scandium oxide:

– 4Sc + 3O₂ → 2Sc₂O₃

Yttrium (Y)

Reaction with oxygen:

– Yttrium reacts with oxygen in the air to form yttrium oxide:

– 4Y + 3O₂ → 2Y₂O₃

Reaction with sulfur:

– Yttrium reacts with sulfur to form yttrium sulfide:

– 3Y + S → Y₂S₃

Lanthanum (La)

Reaction with oxygen:

– Lanthanum reacts with oxygen in the air to form lanthanum oxide:

– 4La + 3O₂ → 2La₂O₃

Reaction with water:

– Lanthanum reacts with water to form lanthanum hydroxide and hydrogen gas:

– 2La + 6H₂O → 2La(OH)₃ + 3H₂

Reaction with acids:

– Lanthanum reacts with acids, such as hydrochloric acid, to form lanthanum chloride and hydrogen gas:

– 2La + 6HCl → 2LaCl₃ + 3H₂

Second Triad: Ti, Zr & Hf

Titanium (Ti)

Reaction with oxygen:

– Titanium reacts with oxygen to form titanium oxide:

– 2Ti + O₂ → 2TiO₂

Reaction with chlorine:

– Titanium reacts with chlorine to form titanium chloride:

– Ti + 2Cl₂ → TiCl₄

Reaction with sulfur:

– Titanium reacts with sulfur to form titanium sulfide:

– Ti + S → TiS

Zirconium (Zr)

Reaction with oxygen:

– Zirconium reacts with oxygen to form zirconium oxide:

– 2Zr + O₂ → 2ZrO₂

Reaction with hydrogen:

– Zirconium reacts with hydrogen to form zirconium hydride:

– Zr + 2H₂ → ZrH₄

Reaction with fluorine:

– Zirconium reacts with fluorine to form zirconium fluoride:

– Zr + 2F₂ → ZrF₄

Hafnium (Hf)

Reaction with oxygen:

– Hafnium reacts with oxygen to form hafnium oxide:

– 2Hf + O₂ → 2HfO₂

Reaction with nitrogen:

– Hafnium reacts with nitrogen to form hafnium nitride:

– Hf + 2N₂ → HfN₄

Reaction with sulfur:

– Hafnium reacts with sulfur to form hafnium sulfide:

– Hf + S → HfS

Third triad: V, Nb & Ta

Vanadium (V)

Reaction with oxygen:

– Vanadium reacts with oxygen to form vanadium pentoxide:

– 2V + 5O₂ → 2V₂O₅

Reaction with hydrochloric acid:

– Vanadium reacts with hydrochloric acid to form vanadium(III) chloride and hydrogen gas:

– V + 3HCl → VCl₃ + H₂

Reaction with sulfuric acid:

– Vanadium reacts with sulfuric acid to form vanadium(IV) sulfate and water:

– V + H₂SO₄ → VSO₄ + H₂O

Niobium (Nb)

Reaction with oxygen:

– Niobium reacts with oxygen to form niobium pentoxide:

– 4Nb + 5O₂ → 2Nb₂O₅

Reaction with chlorine:

– Niobium reacts with chlorine to form niobium chloride:

– Nb + 3Cl₂ → NbCl₅

Reaction with hydrogen:

– Niobium reacts with hydrogen to form niobium hydride:

– Nb + 2H₂ → NbH₄

Tantalum (Ta)

Reaction with oxygen:

– Tantalum reacts with oxygen to form tantalum pentoxide:

– 2Ta + 5O₂ → 2Ta₂O₅

Reaction with hydrochloric acid:

– Tantalum reacts with hydrochloric acid to form tantalum(III) chloride and hydrogen gas:

– Ta + 6HCl → TaCl₃ + 3H₂

Reaction with sulfuric acid:

– Tantalum reacts with sulfuric acid to form tantalum(IV) sulfate and water:

– Ta + 2H₂SO₄ → Ta(SO₄)₂ + 2H₂O

Fourth triad: Cr, Mo & W

Chromium (Cr)

Reaction with oxygen:

– Chromium reacts with oxygen to form chromium(III) oxide:

– 4Cr + 3O₂ → 2Cr₂O₃

Reaction with hydrochloric acid:

– Chromium reacts with hydrochloric acid to form chromium(III) chloride and hydrogen gas:

– 2Cr + 6HCl → 2CrCl₃ + 3H₂

Reaction with sulfuric acid:

– Chromium reacts with sulfuric acid to form chromium(III) sulfate and water:

– Cr + 3H₂SO₄ → Cr₂(SO₄)₃ + 3H₂O

Reaction with sulfur:

– Chromium reacts with sulfur to form chromium sulfide:

– Cr + S → CrS

Formation of chromate compounds:

– Chromium can form chromate compounds, such as potassium chromate (K₂CrO₄) and sodium chromate (Na₂CrO₄), by reacting with appropriate reagents.

Molybdenum (Mo)

Reaction with oxygen:

– Molybdenum reacts with oxygen to form molybdenum trioxide:

– 2Mo + 3O₂ → 2MoO₃

Reaction with hydrogen:

– Molybdenum reacts with hydrogen to form molybdenum hydride:

– Mo + 3H₂ → MoH₆

Reaction with chlorine:

– Molybdenum reacts with chlorine to form molybdenum chloride:

– Mo + 3Cl₂ → MoCl₆

Reaction with sulfur:

– Molybdenum reacts with sulfur to form molybdenum sulfide:

– Mo + 2S → MoS₂

Formation of molybdate compounds:

– Molybdenum can form molybdate compounds, such as ammonium molybdate [(NH₄)₂MoO₄] and sodium molybdate (Na₂MoO₄), by reacting with appropriate reagents.

Tungsten (W)

Reaction with oxygen:

– Tungsten reacts with oxygen to form tungsten trioxide:

– 2W + 3O₂ → 2WO₃

Reaction with hydrochloric acid:

– Tungsten reacts with hydrochloric acid to form tungsten(IV) chloride and hydrogen gas:

– W + 4HCl → WCl₄ + 2H₂

Reaction with sulfuric acid

– Tungsten reacts with sulfuric acid to form tungsten(VI) sulfate and water:

– W + 6H₂SO₄ → W(SO₄)₆ + 6H₂O

Reaction with chlorine:

– Tungsten reacts with chlorine to form tungsten chloride:

– W + 3Cl₂ → WCl₆

Formation of tungstate compounds:

– Tungsten can form tungstate compounds, such as sodium tungstate (Na₂WO₄) and calcium tungstate (CaWO₄), by reacting with appropriate reagents.

Fifth triad: Mn, Tc & Re

Manganese (Mn)

Reaction with oxygen:

– Manganese reacts with oxygen to form manganese(IV) oxide:

– 2Mn + O₂ → 2MnO₂

Reaction with hydrochloric acid:

– Manganese reacts with hydrochloric acid to form manganese(II) chloride and hydrogen gas:

– Mn + 2HCl → MnCl₂ + H₂

Reaction with sulfuric acid:

– Manganese reacts with sulfuric acid to form manganese(II) sulfate and water:

– Mn + H₂SO₄ → MnSO₄ + H₂O

Technetium (Tc)

Radioactive decay:

– Technetium undergoes radioactive decay to form other elements or isotopes.

Reaction with oxygen:

– Technetium reacts with oxygen to form technetium dioxide:

– Tc + O₂ → TcO₂

Complex formation:

– Technetium can form various complexes with ligands, such as ammonia or carbon monoxide.

Rhenium (Re)

Reaction with oxygen:

– Rhenium reacts with oxygen to form rhenium(VII) oxide:

– 2Re + 7O₂ → 2Re₂O₇

Reaction with hydrochloric acid:

– Rhenium reacts with hydrochloric acid to form rhenium(IV) chloride and hydrogen gas:

– Re + 2HCl → ReCl₄ + H₂

Formation of carbonyl complexes:

– Rhenium can form carbonyl complexes by reacting with carbon monoxide.

Sixth triad: Fe, Ru & Os

Iron (Fe)

Reaction with oxygen:

– Iron reacts with oxygen to form iron(III) oxide:

– 4Fe + 3O₂ → 2Fe₂O₃

Reaction with hydrochloric acid:

– Iron reacts with hydrochloric acid to form iron(II) chloride and hydrogen gas:

– Fe + 2HCl → FeCl₂ + H₂

Reaction with sulfuric acid:

– Iron reacts with sulfuric acid to form iron(II) sulfate and hydrogen gas:

– Fe + H₂SO₄ → FeSO₄ + H₂

Ruthenium (Ru)

Reaction with oxygen:

– Ruthenium reacts with oxygen to form ruthenium(IV) oxide:

– Ru + 2O₂ → RuO₂

Reaction with hydrochloric acid:

– Ruthenium reacts with hydrochloric acid to form ruthenium(III) chloride and hydrogen gas:

– Ru + 6HCl → RuCl₃ + 3H₂

Osmium (Os)

Reaction with oxygen:

– Osmium reacts with oxygen to form osmium tetroxide:

– 2Os + 5O₂ → 2OsO₄

Reaction with hydrochloric acid:

– Osmium reacts with hydrochloric acid to form osmium tetrachloride and hydrogen gas:

– Os + 4HCl → OsCl₄ + 2H₂

Reaction with sodium:

– Osmium reacts with sodium to form sodium osmiumate:

– 2Os + 4Na → 2Na₂Os

Seventh triad: Co, Rh & Ir

Cobalt (Co)

Reaction with oxygen:

– Cobalt reacts with oxygen to form cobalt(II) oxide and cobalt(III) oxide:

– 2Co + O₂ → 2CoO

– 4Co + 3O₂ → 2Co₂O₃

Reaction with hydrochloric acid:

– Cobalt reacts with hydrochloric acid to form cobalt(II) chloride and hydrogen gas:

– Co + 2HCl → CoCl₂ + H₂

Reaction with sulfuric acid:

– Cobalt reacts with sulfuric acid to form cobalt(II) sulfate and hydrogen gas:

– Co + H₂SO₄ → CoSO₄ + H₂

Rhodium (Rh):

Reaction with oxygen:

– Rhodium reacts with oxygen to form rhodium(III) oxide:

– 2Rh + 3O₂ → 2Rh₂O₃

Reaction with chlorine:

– Rhodium reacts with chlorine to form rhodium(III) chloride:

– 2Rh + 3Cl₂ → 2RhCl₃

Reaction with hydrogen:

– Rhodium reacts with hydrogen to form rhodium hydride:

– Rh + H₂ → RhH₂

Reaction with hydrochloric acid:

– Rhodium reacts with hydrochloric acid to form rhodium(III) chloride and hydrogen gas:

– 2Rh + 6HCl → 2RhCl₃ + 3H₂

Iridium (Ir)

Reaction with oxygen:

– Iridium reacts with oxygen to form iridium(IV) oxide:

– 2Ir + 5O₂ → 2IrO₂

Reaction with halogens:

– Iridium reacts with halogens (e.g., chlorine) to form iridium(IV) halides:

– Ir + 2Cl₂ → IrCl₄

Reaction with hydrochloric acid:

– Iridium reacts with hydrochloric acid to form iridium(III) chloride and hydrogen gas:

– Ir + 3HCl → IrCl₃ + H₂

Formation of iridium tetroxide:

– Iridium reacts with oxygen to form iridium tetroxide, a highly toxic compound:

– 2Ir + 4O₂ → 2IrO₄

Reaction with aqua regia:

– Iridium reacts with aqua regia (a mixture of nitric acid and hydrochloric acid) to form soluble iridium(III) chloride:

– Ir + 4HCl + HNO₃ → IrCl₃ + NO + 2H₂O

Eighth triad: Ni, Pd & Pt

Nickel (Ni)

Reaction with oxygen:

– Nickel reacts with oxygen to form nickel(II) oxide:

– 2Ni + O₂ → 2NiO

Reaction with hydrochloric acid:

– Nickel reacts with hydrochloric acid to form nickel(II) chloride and hydrogen gas:

– Ni + 2HCl → NiCl₂ + H₂

Reaction with sulfuric acid:

– Nickel reacts with sulfuric acid to form nickel(II) sulfate and hydrogen gas:

– Ni + H₂SO₄ → NiSO₄ + H₂

Reaction with ammonia:

– Nickel reacts with ammonia to form a complex ion:

– Ni + 6NH₃ → [Ni(NH₃)₆]²⁺

Palladium (Pd)

Reaction with oxygen:

– Palladium reacts with oxygen to form palladium(II) oxide:

– 2Pd + O₂ → 2PdO

Reaction with hydrogen:

– Palladium reacts with hydrogen to form palladium hydride:

– Pd + H₂ → PdH₂

Reaction with hydrochloric acid:

– Palladium reacts with hydrochloric acid to form palladium(II) chloride and hydrogen gas:

– Pd + 2HCl → PdCl₂ + H₂

Reaction with nitric acid:

– Palladium reacts with concentrated nitric acid to form palladium(II) nitrate:

– Pd + 4HNO₃ → Pd(NO₃)₂ + 2NO₂ + 2H₂O

Reaction with sodium hydroxide:

– Palladium reacts with sodium hydroxide to form palladium(II) hydroxide:

– Pd + 2NaOH → Pd(OH)₂ + 2Na

Platinum (Pt)

Reaction with oxygen:

– Platinum reacts with oxygen to form platinum(IV) oxide:

– 2Pt + 5O₂ → 2PtO₂

Reaction with hydrochloric acid:

– Platinum reacts with aqua regia (a mixture of hydrochloric acid and nitric acid) to form chloroplatinic acid:

– Pt + 4HCl + 2HNO₃ → H₂PtCl₆ + 2NO₂ + 2H₂O

Reaction with sulfuric acid:

– Platinum reacts with hot concentrated sulfuric acid to form platinum(IV) sulfate:

– Pt + 4H₂SO₄ → Pt(SO₄)₂ + 4H₂O

Reaction with sodium cyanide:

– Platinum reacts with sodium cyanide to form a soluble complex:

– Pt + 2NaCN → Na₂[Pt(CN)₄]

Ninth triad: Cu, Ag, Au

Copper (Cu)

Reaction with oxygen:

– Copper reacts with oxygen in the air to form copper(II) oxide:

– 4Cu + O₂ → 2Cu₂O

Reaction with sulfuric acid:

– Copper reacts with sulfuric acid to form copper(II) sulfate, sulfur dioxide, and water:

– Cu + H₂SO₄ → CuSO₄ + SO₂ + H₂O

Reaction with nitric acid:

– Copper reacts with concentrated nitric acid to form copper(II) nitrate, nitrogen dioxide, and water:

– 3Cu + 8HNO₃ → 3Cu(NO₃)₂ + 2NO₂ + 4H₂O

Reaction with silver nitrate:

– Copper reacts with silver nitrate to form copper(II) nitrate and silver:

– Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag

Silver (Ag)

Reaction with oxygen:

– Silver does not react with oxygen at normal temperatures, but it tarnishes in the presence of sulfur compounds in the air.

Reaction with hydrochloric acid:

– Silver does not react with dilute hydrochloric acid, but it reacts with concentrated hydrochloric acid to form silver chloride and hydrogen gas:

– 2Ag + 4HCl → 2AgCl + 2H₂

Reaction with sulfuric acid:

– Silver does not react with dilute sulfuric acid, but it reacts with concentrated sulfuric acid to form silver sulfate and sulfur dioxide:

– 2Ag + 2H₂SO₄ → Ag₂SO₄ + 2H₂O + SO₂

Reaction with cyanide:

– Silver reacts with cyanide to form a soluble complex ion:

– Ag + CN⁻ → [Ag(CN)₂]⁻

Gold (Au)

Reaction with aqua regia:

– Gold reacts with aqua regia (a mixture of concentrated nitric acid and hydrochloric acid) to form gold(III) chloride:

– 4Au + 8HCl + 2HNO₃ → 4AuCl₃ + 2NO + 4H₂O

Reaction with cyanide:

– Gold reacts with cyanide to form a soluble complex ion:

– Au + CN⁻ → [Au(CN)₂]⁻

Reaction with sulfuric acid:

– Gold does not react with sulfuric acid under normal conditions.

Reaction with oxygen:

– Gold does not react with oxygen at normal temperatures and does not tarnish.

Reaction with mercury:

– Gold reacts with mercury to form an amalgam:

– Au + Hg → AuHg

10. Tenth triad: Zn, Cd & Hg

Zinc (Zn)

Reaction with hydrochloric acid:

– Zinc reacts with hydrochloric acid to form zinc chloride and hydrogen gas:

– Zn + 2HCl → ZnCl₂ + H₂

Reaction with sulfuric acid:

– Zinc reacts with sulfuric acid to form zinc sulfate and hydrogen gas:

– Zn + H₂SO₄ → ZnSO₄ + H₂

Reaction with oxygen:

– Zinc reacts with oxygen in the air to form zinc oxide:

– 2Zn + O₂ → 2ZnO

Reaction with water:

– Zinc reacts slowly with water to form zinc hydroxide and hydrogen gas:

– Zn + 2H₂O → Zn(OH)₂ + H₂

Cadmium (Cd)

Reaction with hydrochloric acid:

– Cadmium reacts with hydrochloric acid to form cadmium chloride and hydrogen gas:

– Cd + 2HCl → CdCl₂ + H₂

Reaction with sulfuric acid:

– Cadmium reacts with sulfuric acid to form cadmium sulfate and hydrogen gas:

– Cd + H₂SO₄ → CdSO₄ + H₂

Reaction with oxygen:

– Cadmium reacts with oxygen in the air to form cadmium oxide:

– 2Cd + O₂ → 2CdO

Reaction with water:

– Cadmium reacts slowly with water to form cadmium hydroxide and hydrogen gas:

– Cd + 2H₂O → Cd(OH)₂ + H₂

Mercury (Hg)

Reaction with nitric acid:

– Mercury reacts with nitric acid to form mercury(II) nitrate, nitrogen dioxide, and water:

– Hg + 4HNO₃ → Hg(NO₃)₂ + 2NO₂ + 2H₂O

Reaction with chlorine:

– Mercury reacts with chlorine to form mercury(II) chloride:

– Hg + Cl₂ → HgCl₂

Reaction with sulfur:

– Mercury reacts with sulfur to form mercury(II) sulfide:

– Hg + S → HgS

Reaction with oxygen:

– Mercury reacts with oxygen in the air to form mercury(II) oxide:

– 2Hg + O₂ → 2HgO

Applications of d block Elements

3d	4d	5d
Scandium (Sc) 21 Alloying agent in aerospace components, Laser material, Catalyst in organic chemistry.	Yttrium (Y) 39 Phosphors for display devices, Catalyst in polymerization reactions, Stabilizer in ceramics.	Lanthanum (La) 57 High-refractive-index glass manufacturing, Battery electrodes, Hydrogen storage materials.
Titanium (Ti) 22 Aerospace and marine applications, Biomedical implants, Pigments and coatings.	Zirconium (Zr) 40 Nuclear reactor components, Corrosion-resistant alloys, Ceramic materials.	Hafnium (Hf) 72 Nuclear reactor control rods, Gas turbines, Superalloys.
Vanadium (V) 23 Steel alloys, Vanadium redox batteries, Catalyst for chemical reactions.	Niobium (Nb) 41 Superconducting magnets, Alloys for jet engines and rockets, Electronic components.	Tantalum (Ta) 73 High-temperature applications, Electronic capacitors, Chemical processing equipment.
Chromium (Cr) 24 Stainless steel production, Decorative coatings, Corrosion protection.	Molybdenum (Mo) 42 High-strength alloys, Catalysts in chemical reactions, Electronic and electrical applications.	Tungsten (W) 74 High-temperature applications, Electrical contacts, Radiation shielding.
Manganese (Mn) 25 Steel production Battery cathodes, Chemical oxidizing agent.	Technetium (Tc) 43 Medical imaging (radioisotope), Industrial catalysts, Research in nuclear physics.	Rhenium (Re) 75 Superalloys for aerospace, Catalysts in fine chemical synthesis, Electrical contact materials.
Iron (Fe) 26 Construction materials, Manufacturing of steel, Magnetic alloys.	Ruthenium (Ru) 44 Electroplating catalyst, Chemical catalysts, Anticancer drugs.	Osmium (Os) 76 Electronics and electrical contacts, Hardening agent for alloys, Medical implants.
Cobalt (Co) 27 High-strength magnets, Rechargeable batteries, Catalysts in petrochemical processes.	Rhodium (Rh) 45 Automotive catalytic converters, Jewelry and decorative plating, Chemical catalysts.	Iridium (Ir) 77 Spark plugs and electrical contacts, Cancer treatment drugs, Industrial catalysts.
Nickel (Ni) 28 Stainless steel production, Battery materials, Corrosion-resistant coatings.	Palladium (Pd) 46 Automotive catalytic converters, Fuel cell catalysts, Electronics manufacturing.	Platinum (Pt) 78 Chemical catalysts, Jewelry and investment, Fuel cell technology.
Copper (Cu) 29 Electrical wiring and conductivity, Electronic circuitry, Plumbing and piping.	Silver (Ag) 47 Jewelry and silverware, Photography and imaging, Electrical contacts.	Gold (Au) 79 Jewelry and decoration, Electronics and electrical contacts.
Zinc (Zn) 30 Galvanizing coatings, Batteries and metal alloys, Pharmaceuticals and dietary supplements.	Cadmium (Cd) 48 Nickel-cadmium batteries, Pigments and coatings, Solar cells.	Mercury (Hg) 80 Thermometers and barometers, Electrical switches, Industrial chemical processes.