Iridium
Simplified 2D Bohr model:Central red circle is the nucleus (proton). Blue ring represents the electron's orbit. Small blue dot is the electron. Note: This basic model doesn't show quantum behavior.
CLASSIFICATION:
Transition Metal
Belonging to the esteemed platinum group, Iridium boasts remarkable properties like high density, exceptional melting point, and unparalleled resistance to corrosion.
192.217 u
Appearance: Silvery-white, lustrous metal
Iridium, a member of the platinum group metals, stands out with its silvery-white luster, extreme hardness, and brittleness. It reigns supreme as the most corrosion-resistant metal known, making it invaluable in high-temperature applications, electrical contacts, and as a hardening agent for platinum alloys.
77
77
115
eV
4. Discovery and History
2446 °C
4428 °C
22.56 g/cm³
136 pm
8.52 cm³/mol
137 pm (estimated)
25.10 J/(mol·K)
147 W/(m·K)
4825 m/s (estimated)
22.56 g/cm³
6.5
147 W/(m·K)
1670 MPa
0.131 J/(g·K)
6.4 µm/(m·K)
Solid to liquid at 2446 °C and liquid to gas at 4428 °C under standard pressure.
Extremely resistant to corrosion and attack by acids, even at high temperatures.
+3, +4, +6 (less common)
Values vary depending on the specific compound and reaction.
Iridium's chemical inertness is its defining characteristic. It primarily forms compounds in the +3 and +4 oxidation states, showcasing its reluctance to engage in chemical reactions.
Weakly paramagnetic, meaning it is attracted to magnetic fields but only to a small extent.
47.1 nΩ·m, indicating it is a good conductor of electricity.
Positive, suggesting that holes (electron vacancies) are the dominant charge carriers in iridium.
Values vary depending on the wavelength of light and the specific compound.
High reflectivity, especially for infrared radiation, making it suitable for use in infrared optics and reflective coatings.
Iridium and its compounds exhibit complex absorption spectra, with specific absorption bands depending on the electronic structure and oxidation state.
n=6 for Iridium's outermost electrons, indicating its period in the periodic table. (l=2 for the d orbital, reflecting its transition metal characteristics.)
Total Electrons: 77, Shells: 2, 8, 18, 32, 15, 2
Complex energy level structure due to the presence of partially filled d orbitals, leading to various electronic transitions and spectral lines.
[Xe] 4f14 5d7 6s2
Iridium's electron configuration places it within the d-block of the periodic table, explaining its characteristic properties of high density, high melting point, and variable oxidation states.
Found in Ores with Other Platinum Group Metals
Iridium is primarily found in nature alloyed with other platinum group metals, such as osmium, platinum, and ruthenium. It occurs in trace amounts within nickel and copper deposits and is also found in placer deposits.
Face-Centered Cubic (FCC)
Temperature: At room temperature and under normal conditions
Iridium adopts a face-centered cubic crystal structure, similar to other platinum group metals. This arrangement contributes to its strength, density, and high melting point.
+4, +3, +6
The most common oxidation state for iridium, observed in compounds like iridium dioxide (IrO2)., Another frequently encountered oxidation state, as seen in iridium trichloride (IrCl3)., Less common but observed in compounds like iridium hexafluoride (IrF6), highlighting iridium's ability to exhibit a wider range of oxidation states compared to lighter platinum group metals.
Iridium(III) Chloride (IrCl3)
IrCl3
A versatile catalyst in organic synthesis, facilitating reactions like hydrogenation and carbonylation.
Iridium(IV) Oxide (IrO2)
IrO2
Plays a crucial role in electrochemical applications, particularly in electrodes for electrolyzers and chlor-alkali cells.
Iridium Hexafluoride (IrF6)
IrF6
A highly reactive compound, demonstrating the less common +6 oxidation state of iridium.
Vaska's Complex (IrCl(CO)[P(C6H5)3]2)
IrCl(CO)[P(C6H5)3]2
A renowned organometallic compound used in homogeneous catalysis and research.
208.881 nm nm
Strong
224.268 nm nm
Strong
254.397 nm nm
Medium
17. Practical Applications
High-Temperature Materials
Iridium's exceptional resistance to heat makes it ideal for crucibles, electrodes, and other equipment operating at extreme temperatures.
Electrical Contacts
Its hardness and corrosion resistance make iridium perfect for electrical contacts and electrodes in spark plugs, switches, and other devices.
Medical Devices
Iridium-192, a radioactive isotope, is employed in brachytherapy for cancer treatment, delivering targeted radiation to tumors.
Catalysis
Iridium compounds serve as catalysts in various industrial processes, including petroleum refining, chemical production, and automotive catalytic converters.
Alloy Hardening
Adding iridium to platinum and other metals enhances their strength and durability, making them suitable for jewelry, medical implants, and specialized equipment.
26. Synthesis and Production
Iridium is not synthesized but rather extracted from natural ores. It is primarily obtained as a byproduct of nickel and copper mining and processing.
The extraction process involves several steps, including: 1) Concentration of the ore through flotation or other methods. 2) Dissolution of the concentrate using aqua regia or other strong acids. 3) Separation of iridium from other platinum group metals using complex chemical processes, such as solvent extraction and precipitation.
Global iridium production is limited, estimated to be around 7-10 tons per year. The complex extraction process and the rarity of iridium-containing ores contribute to its limited availability.
20. Economic Data
Market Price: Highly variable but generally expensive due to its rarity and complex extraction process. Prices fluctuate based on supply and demand dynamics.
Producing Countries: South Africa, Russia, and Canada are the primary producers of iridium.
Industrial Use: Employed in high-performance alloys, electrical contacts, catalysis, and various specialized applications.
Description: Iridium's scarcity and exceptional properties contribute to its high economic value. Its use is often limited to applications where its unique characteristics are essential.
18. Biological Role
Not biologically significant
Iridium has no known biological role in living organisms. It is not an essential element for life processes.
Subject to regulations related to the mining, processing, and handling of precious metals, as well as those governing hazardous materials. Specific regulations vary depending on the country or region.
Trade and export of iridium may be subject to restrictions due to its strategic importance in various industries and its potential use in nuclear applications.
19. Health and Environmental Impact
Metallic iridium is considered non-toxic, but precautions are crucial when handling its compounds due to potential health hazards.
The environmental impact of iridium is primarily associated with the mining and refining processes, which can lead to habitat disruption and pollution if not managed responsibly. Iridium itself is not considered a significant environmental hazard due to its low reactivity and limited use.
27. Environmental Safety
While metallic iridium is generally non-toxic, its compounds, especially in powder or dust form, can be hazardous if inhaled or ingested. Exposure may cause irritation to the eyes, skin, and respiratory system.
Handling iridium compounds requires proper safety measures, including adequate ventilation, protective clothing, and respiratory protection when necessary. It's crucial to prevent the formation and inhalation of dust.
Handling: Handle iridium and its compounds with care, particularly in powder or dust form. Avoid inhalation, ingestion, and skin contact. Use appropriate personal protective equipment, including gloves, safety glasses, and respiratory protection when necessary.
Storage: Store iridium and its compounds in a cool, dry place, away from incompatible materials and potential ignition sources. Keep containers tightly sealed to prevent dust formation.
First Aid Measures: In case of exposure, seek medical attention immediately. For inhalation, move to fresh air and seek medical attention. For skin contact, wash thoroughly with soap and water. For eye contact, flush with plenty of water for at least 15 minutes and seek medical attention.
23. Future Predictions
Increased demand for iridium is expected in the future, driven by its growing applications in catalysis, electronics, and other high-tech industries.
N/A
Research efforts may focus on developing more efficient and sustainable methods for iridium extraction and recycling to address concerns over its limited supply.
N/A
Exploration for new iridium deposits and advancements in asteroid mining technologies could potentially expand the available resources of this valuable metal.
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