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Intro to Chemistry
Table of Contents
Unit 19 Overview: Transition Metals & Coordination Compounds
19.1 Occurrence, Preparation, and Properties of Transition Metals and Their Compounds
19.2 Coordination Chemistry of Transition Metals
19.3 Spectroscopic and Magnetic Properties of Coordination Compounds

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19.1 Occurrence, Preparation, and Properties of Transition Metals and Their Compounds

Citation:

Transition metals, found in the d-block of the periodic table, boast unique properties like high melting points, variable oxidation states, and colorful compounds. These metals form the backbone of many industrial processes and biological systems, making them crucial in chemistry and beyond.

From iron extraction in blast furnaces to copper purification through electrolysis, transition metals undergo complex refining processes. Their diverse oxidation states influence the behavior of halides, oxides, and salts, while their applications range from catalysis to essential biological functions like oxygen transport in hemoglobin.

Transition Metals and Their Compounds

Properties of transition metals

  • Transition metals are elements in the d-block of the periodic table have partially filled d orbitals in their neutral or cationic states
  • Common properties of transition metals include:
    • High melting and boiling points due to strong metallic bonding (tungsten, melting point: 3422°C)
    • High densities resulting from close packing of atoms (osmium, density: 22.59 g/cm³)
    • High tensile strengths attributed to strong metallic bonding (steel, tensile strength: 400-2000 MPa)
    • Ductility and malleability allow them to be drawn into wires or hammered into sheets (copper wires, gold foil)
    • Good electrical and thermal conductivity due to delocalized electrons (silver, electrical conductivity: 6.30 × 10⁷ S/m)
  • Variable oxidation states enable transition metals to form stable compounds in multiple oxidation states due to small energy differences between their d orbitals (manganese: +2, +3, +4, +6, +7)
  • Formation of colored compounds occurs because the presence of unpaired d electrons allows for d-d electronic transitions that absorb specific wavelengths of visible light, resulting in the appearance of color (copper(II) sulfate, blue)
  • Formation of coordination compounds happens when transition metals form complexes with ligands (ions or molecules that donate electron pairs) where the metal ion acts as a Lewis acid, accepting electron pairs from the ligands through coordinate covalent bonds (hemoglobin, iron complexed with porphyrin ligand)
  • Electron configuration plays a crucial role in determining the properties and reactivity of transition metals

Extraction of iron, copper and silver

  • Iron extraction and refining involves:
    1. Concentrating the ore hematite ($Fe_2O_3$) through froth flotation and magnetic separation
    2. Reducing concentrated ore with coke (carbon) in a blast furnace at high temperatures: $Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2$
    3. Collecting molten iron at the bottom of the furnace for further refining to produce steel
  • Copper extraction and refining involves:
    1. Concentrating the sulfide ore chalcopyrite ($CuFeS_2$) through froth flotation
    2. Roasting concentrated ore to convert sulfides to oxides: $2CuFeS_2 + 4O_2 \rightarrow Cu_2S + 2FeO + 3SO_2$
    3. Smelting roasted ore in a furnace with silica ($SiO_2$) to remove iron as slag
    4. Purifying molten copper through electrolytic refining
  • Silver extraction and refining involves:
    1. Extracting silver as a byproduct of lead, zinc, or copper mining from the ore argentite ($Ag_2S$)
    2. Treating crushed ore with a sodium cyanide ($NaCN$) solution to form a soluble silver-cyanide complex: $Ag_2S + 4NaCN \rightarrow 2Na[Ag(CN)_2] + Na_2S$
    3. Recovering silver from the solution by displacement with zinc or through electrolysis
  • These extraction processes are examples of metallurgy, the science of extracting metals from their ores

Oxidation states in transition metals

  • Halides exhibit different behavior based on oxidation state:
    • Lower oxidation states tend to form ionic halides (iron(II) chloride, $FeCl_2$)
    • Higher oxidation states form covalent halides (iron(III) chloride, $FeCl_3$)
  • Oxides show varying acidity based on oxidation state:
    • Lower oxidation states form basic oxides (chromium(III) oxide, $Cr_2O_3$)
    • Higher oxidation states form acidic oxides (chromium(VI) oxide, $CrO_3$)
  • Salts have stability dependent on the metal's oxidation state and the anion's nature:
    • Higher oxidation states generally form more stable salts with oxoanions (anions containing oxygen)
      • Manganese(II) sulfate ($MnSO_4$) is stable
      • Manganese(VII) sulfate ($Mn_2(SO_4)_3$) is unstable and acts as a strong oxidizing agent

Applications of Transition Metals

  • Transition metals and their compounds are widely used in catalysis, participating in redox reactions to facilitate chemical transformations in industrial processes
  • Many transition metal complexes serve as important ligands in biological systems, such as the iron-containing heme group in hemoglobin

Key Terms to Review (49)

Actinoid series: The actinoid series consists of 15 metallic elements from atomic numbers 89 to 103, starting with actinium and ending with lawrencium. These elements are known for their radioactive properties and are typically found in the f-block of the periodic table.
Actinide series: The actinide series consists of 15 metallic elements from actinium (Ac) to lawrencium (Lr) in the periodic table. These elements are characterized by their filling of the 5f electron orbital.
Electron configuration: Electron configuration describes the distribution of electrons in an atom's orbitals. It follows principles such as the Aufbau principle, Pauli exclusion principle, and Hund's rule.
D-block elements: D-block elements are those elements in groups 3-12 of the periodic table, characterized by having their outermost electrons in a d orbital. They include transition metals known for their ability to form various oxidation states and complex compounds.
First transition series: The first transition series includes the 10 elements from Scandium (Sc) to Zinc (Zn) in the fourth period of the periodic table. These elements are characterized by their partially filled d-orbitals.
Fourth transition series: The fourth transition series consists of the elements in the periodic table from hafnium (Hf) to rutherfordium (Rf), which occupy the 5d block. These metals exhibit typical properties of transition metals, such as variable oxidation states and the formation of colored compounds.
Hydrometallurgy: Hydrometallurgy is a method used in extracting metals from their ores through the use of aqueous chemistry. It involves processes like leaching, solution concentration and purification, and metal recovery.
Lanthanoid series: The lanthanoid series consists of 15 metallic elements with atomic numbers from 57 to 71, starting with lanthanum and ending with lutetium. These elements are known for their similar properties and are also referred to as rare earth elements.
Inner transition metals: Inner transition metals are elements found in the f-block of the periodic table, comprising the lanthanides and actinides. They are characterized by having electrons fill their f-orbitals.
Lanthanide series: The lanthanide series consists of 15 metallic elements with atomic numbers 57 through 71, from lanthanum (La) to lutetium (Lu). They are known for their similar properties and are often found together in various minerals.
Rare earth elements: Rare earth elements are a set of 17 chemical elements in the periodic table, specifically the 15 lanthanides plus scandium and yttrium. These elements are crucial in various high-tech industries due to their unique magnetic, luminescent, and electrochemical properties.
Smelting: Smelting is a metallurgical process that involves heating ores to extract base metals. It typically involves the reduction of metal compounds to elemental metals using a chemical reducing agent.
Steel: Steel is an alloy primarily composed of iron and carbon, known for its high tensile strength and versatility. It is widely used in construction, tools, and various industries due to its durability and adaptability.
Superconductor: A superconductor is a material that can conduct electricity without resistance below a certain critical temperature. This property allows it to maintain an electric current with no energy loss.
Second transition series: The second transition series consists of the elements from Yttrium (Y) to Cadmium (Cd) in the periodic table. These elements are characterized by their d-orbitals being filled after the 4th period.
Third transition series: The third transition series consists of the transition metals in the sixth period of the periodic table, spanning from hafnium (Hf) to mercury (Hg). These elements are characterized by partially filled d-orbitals.
Metallurgy: Metallurgy is the science and technology of extracting metals from their ores, refining them, and creating useful alloys. It encompasses the study of the physical and chemical properties of metals, as well as the processes involved in their production, processing, and application across various industries.
Iron: Iron is a chemical element that is essential for many vital processes in the human body. It is a transition metal that plays a crucial role in various topics in chemistry, including atomic structure, the periodic table, chemical nomenclature, corrosion, periodicity, and the occurrence, preparation, and properties of transition metals and their compounds.
Gold: Gold is a precious, dense, and highly valued metal that has been prized throughout human history for its unique properties and applications. It is a transition metal that is widely used in various industries, from jewelry and electronics to medicine and dentistry.
Electron Configuration: Electron configuration is the arrangement of electrons in an atom's electron shells and subshells, which determines the atom's chemical properties and behavior. This concept is fundamental to understanding the periodic table, periodic trends, and the reactivity of elements.
D-block: The d-block, also known as the transition metals, is a group of elements in the periodic table that are characterized by the filling of the 3d, 4d, and 5d electron shells. These elements exhibit unique chemical and physical properties that make them essential in various applications and industries.
Copper: Copper is a reddish-brown metallic element that is an essential mineral for human health and has numerous applications in various industries. It is a transition metal that exhibits unique chemical properties, making it an important component in many chemical processes and technological advancements.
Redox Reactions: Redox (reduction-oxidation) reactions are a fundamental type of chemical reaction where the transfer of electrons occurs between two or more reactants. In these reactions, one substance is oxidized (loses electrons) while another is reduced (gains electrons), maintaining the overall charge balance.
Catalysis: Catalysis is the process by which a substance, called a catalyst, increases the rate of a chemical reaction without being consumed or altered itself. Catalysts work by providing an alternative pathway for the reaction, lowering the activation energy required and allowing the reaction to proceed more quickly.
Silver: Silver is a lustrous, soft, and malleable transition metal with a wide range of applications in various industries, including electronics, jewelry, and photography. It is known for its unique properties, such as high electrical and thermal conductivity, as well as its antimicrobial and corrosion-resistant characteristics.
Osmium: Osmium is a rare, hard, and dense transition metal that is part of the platinum group. It is known for its unique properties and applications in various industries.
Transition Metals: Transition metals are a group of elements in the periodic table that are characterized by their partially filled d-orbitals and ability to form various oxidation states. They exhibit unique chemical and physical properties that make them essential for numerous applications in science, industry, and everyday life.
Tungsten: Tungsten is a dense, hard, and refractory transition metal that is found in the Earth's crust. It has a high melting point, excellent thermal and electrical conductivity, and is used in a variety of industrial and technological applications.
Blast Furnace: A blast furnace is a large, vertical shaft furnace used in the primary production of metals, particularly iron, from their ores. It is a critical component in the extraction and preparation of many representative and transition metals.
Smelting: Smelting is a pyrometallurgical process that involves the thermal extraction and reduction of metals from their ores or concentrates. It is a crucial step in the production of many metals, including those found in representative and transition metal groups.
Iron(III) Chloride: Iron(III) chloride, also known as ferric chloride, is a chemical compound consisting of iron and chlorine. It is a transition metal compound that is widely used in various industrial and scientific applications due to its unique properties and reactivity.
Manganese(VII) Sulfate: Manganese(VII) sulfate, also known as permanganate sulfate, is a transition metal compound that consists of a manganese atom in its highest oxidation state (+7) bonded to four oxygen atoms and a sulfate group. It is an important compound in the context of the occurrence, preparation, and properties of transition metals and their compounds. Manganese(VII) sulfate is a powerful oxidizing agent and finds various applications in chemistry, including as an analytical reagent, disinfectant, and water treatment agent.
Copper(II) Sulfate: Copper(II) sulfate is a chemical compound with the formula CuSO4, consisting of copper, sulfur, and oxygen. It is a blue crystalline solid that is widely used in various applications, including agriculture, water treatment, and the production of other copper compounds.
Sodium Cyanide: Sodium cyanide is an inorganic compound with the chemical formula NaCN. It is a highly toxic substance that is primarily used in the mining and metallurgical industries, as well as in organic synthesis. Sodium cyanide is an important compound in the context of the occurrence, preparation, and properties of transition metals and their compounds.
Manganese(II) Sulfate: Manganese(II) sulfate is an inorganic compound with the chemical formula MnSO4. It is a transition metal compound that belongs to the group of sulfates and is an important source of the essential trace element manganese.
Chalcopyrite: Chalcopyrite is a copper iron sulfide mineral that is an important ore of copper. It is the most common copper-bearing mineral and a key source of copper, gold, and silver in the context of 19.1 Occurrence, Preparation, and Properties of Transition Metals and Their Compounds.
Hematite: Hematite is a common iron oxide mineral that is the primary ore of iron. It is an important component in the occurrence, preparation, and properties of transition metals and their compounds.
Roasting: Roasting is a metallurgical process that involves the heating of metal ores or concentrates in the presence of air to bring about a thermal decomposition and the removal of volatile substances. This process is commonly used in the extraction and purification of transition metals and their compounds.
Argentite: Argentite is a silver sulfide mineral that is an important ore of silver. It is a key compound in the context of understanding the occurrence, preparation, and properties of transition metals and their compounds.
Iron(II) Chloride: Iron(II) chloride, also known as ferrous chloride, is an inorganic compound with the chemical formula FeCl2. It is a transition metal compound that falls under the broader topics of the occurrence, preparation, and properties of transition metals and their compounds.
Magnetic Separation: Magnetic separation is a technique used to separate and purify materials based on their magnetic properties. It involves the use of magnetic fields to selectively remove or concentrate magnetically susceptible components from a mixture, making it a valuable tool in the context of transition metal extraction and processing.
Coke: Coke is a solid carbonaceous material derived from the destructive distillation of coal. It is a key material used in the production and processing of transition metals and their compounds, particularly in the context of 19.1 Occurrence, Preparation, and Properties of Transition Metals and Their Compounds.
Manganese: Manganese is a hard, brittle, gray-white transition metal that is essential for many biological processes and has numerous industrial applications. It is a key component in the context of the topics 19.1 Occurrence, Preparation, and Properties of Transition Metals and Their Compounds.
Chromium(III) oxide: Chromium(III) oxide, also known as chromic oxide, is a green inorganic compound with the chemical formula Cr2O3. It is a crucial compound in the context of the occurrence, preparation, and properties of transition metals and their compounds.
Chromium(VI) oxide: Chromium(VI) oxide, also known as chromic oxide, is a highly oxidizing compound of chromium in its hexavalent state. It is an important transition metal compound with a range of industrial and chemical applications.
Froth Flotation: Froth flotation is a separation process used to concentrate ores and remove impurities by exploiting the differences in their surface properties. It involves adding chemicals to a slurry of crushed ore, causing valuable minerals to attach to air bubbles and float to the surface, forming a froth that can be collected. This method is particularly significant in extracting transition metals and their compounds from ores, highlighting its relevance in mineral processing and metallurgy.
Electrolytic refining: Electrolytic refining is a process used to purify metals by utilizing electrolysis, where an impure metal serves as the anode and a pure metal layer is deposited at the cathode. This technique is especially significant for extracting high-purity transition metals, as it allows for the separation of valuable metals from impurities through controlled electrical energy. By converting the metal ions back into solid form at the cathode, electrolytic refining produces metals that meet stringent purity standards needed for various industrial applications.
Hemoglobin: Hemoglobin is a complex protein found in red blood cells that is responsible for transporting oxygen from the lungs to the body's tissues and facilitating the return of carbon dioxide from the tissues back to the lungs. This protein contains iron, which plays a crucial role in its ability to bind to oxygen, linking it closely with the properties of transition metals and their coordination chemistry.
Steel: Steel is an alloy primarily composed of iron and carbon, which enhances its strength and durability, making it a crucial material in various industrial applications. The properties of steel can be tailored by adjusting its carbon content and adding other elements, such as manganese, chromium, and nickel, which also connects it to the broader category of transition metals and their compounds. Understanding the occurrence, preparation, and properties of steel is essential for its effective use in construction, manufacturing, and many other fields.