Why Is Tungsten Important in Chemistry and Everyday Life?
Tungsten is a type of chemical element that has a symbol W and an atomic number 74. Tungsten element is amongst the rare metals that are occurring naturally on the Earth and is almost exclusively combined with several other elements in the chemical compounds rather than being alone. It was identified as a newer element in the year 1781 and was first isolated as a metal in the year 1783. Its important ores are wolframite and scheelite. Tungsten has many alloys that have numerous applications which include the incandescent light bulb filaments, X-ray tubes (as both the filament and target), the electrodes in the gas tungsten arc welding, the superalloys, and radiation shielding. Tungsten's hardness and high density also give it some military applications in the penetrating projectiles. Tungsten compounds are also used often as the industrial catalysts. In this article, we will learn about tungsten in detail which includes the tungsten melting point, boiling point, tungsten uses, tungsten properties, and the applications of tungsten.
What is Tungsten?
Tungsten is also known as wolfram, and along with Cr and Mo, it belongs to group 6 of the periodic table. The element tungsten has the atomic number of 74 and the atomic mass of 184. Its two main oxidation states are +4 & +6 and it has five different stable isotopes that are 180 W, 182 W, 183 W, 184 W, and 186 W amongst which 182 W, 184 W, and 186 W are found to be the most abundant at 26.498%, 30.64%, and 28.426% respectively.
Tungsten is much similar to molybdenum chemically and its chemistry is one the most complex amongst the transition elements.
Tungsten is a rare element and has a crystal abundance of around 1.0–1.5 mg kg-1 which is similar to that of its neighbouring elements present in the periodic table, molybdenum.
Tungsten is a strong lithophile element, even though it is a siderophile in the iron meteorites and is markedly less chalcophile than the element molybdenum.
Apart from the sulfides, the element occurs as the W⁴⁺ cation in the rare mineral tungstenite.
Tungsten also has essentially anionic geochemistry which is based on the tungstate WO₄²⁻ ion, wherein the W₆⁺ ion is present in the four- or six-fold coordination.
Let us now look at the physical properties of tungsten and the chemical properties of tungsten in detail.
Properties of Tungsten
Tungsten Uses
Some of the applications of tungsten are as follows:
Tungsten is an economically important metal which is being widely used in the light-bulb filaments, electron and television tubes, several abrasives and special alloys just as steels tool.
Tungsten carbide has a great importance in the metal-works, mining and petroleum industries. Contamination from these sources is therefore possible in industrial and urban areas.
Evidence for the significant biological role for tungsten is not much, which is in contrast to molybdenum, that is an essential trace element, although some minor concentrations in some plants suggest a specialized function that perhaps substitutes molybdenum if there is a deficiency.
There is a limited ecotoxicity data available that anything higher than the trace amounts of tungsten in solution is usually considered to be toxic.
Effects of Tungsten
Since tungsten is a rare metal and its compounds are usually inert, the effects of tungsten on the environment are much limited. The abundance of tungsten in the crust of the Earth is known to be around 1.5 parts per million. It is one of the more rare elements that is found on Earth.
Tungsten was at first believed to be a relatively inert element and an only slightly toxic metal, but at the beginning of the year 2000, the risk presented by the tungsten alloys, its dust and particulates to lead to cancer and several other adverse effects in animals as well as humans have been known from the in vitro and in the vivo experiments. The median lethal dose LD50 is dependant strongly on the animals and the method of administration and varies between 59 mg/kg in intravenous, rabbits and 5000 mg/kg in the tungsten metal powder, intraperitoneal rats. People can be exposed to tungsten even in the workplace by breathing it in, swallowing it, skin contact, and eye contact.
FAQs on Tungsten: Properties, Uses, and Effects in Chemistry
1. What are the key physical and chemical properties of Tungsten that make it unique?
Tungsten (Atomic Number 74) is a remarkable transition metal known for its distinctive properties. Its primary characteristics include:
Highest Melting Point: At 3422°C, it has the highest melting point of all pure metals, making it ideal for high-temperature applications.
High Density: It is exceptionally dense (19.3 g/cm³), comparable to that of gold and uranium.
Extreme Hardness: Pure tungsten is hard, but when combined with carbon to form tungsten carbide, it becomes one of the hardest known materials.
Corrosion Resistance: It exhibits excellent resistance to corrosion and is unaffected by most acids and alkalis at room temperature.
Low Vapour Pressure: Tungsten has the lowest vapour pressure among metals, ensuring it does not easily evaporate at high temperatures.
2. What is the chemical symbol for Tungsten and why is it 'W'?
The chemical symbol for Tungsten is W. This symbol originates from the element's alternate name, Wolfram, which is derived from its primary ore, wolframite. The name wolframite roughly translates to "devourer of tin," as it interfered with the process of tin smelting. While the name 'Tungsten' (from Swedish, meaning "heavy stone") is common in English, the symbol W remains the internationally recognised standard.
3. Where is Tungsten found in nature and how is it commercially extracted?
Tungsten is not found as a free element in nature. It is primarily extracted from two main types of minerals: wolframite ((Fe, Mn)WO₄) and scheelite (CaWO₄). The extraction process involves crushing the ore and treating it with alkalis to produce tungsten trioxide (WO₃). This oxide is then isolated and reduced in a furnace with a stream of hydrogen gas to produce pure tungsten powder, which can then be sintered into solid forms.
4. Why does Tungsten have the highest melting point of all pure metals?
Tungsten's exceptionally high melting point is a direct result of its electronic structure and the resulting strength of its metallic bonds. With an electron configuration of [Xe] 4f¹⁴ 5d⁴ 6s², Tungsten has six valence electrons that participate in forming a very strong metallic bond. This creates a powerful cohesive force holding the atoms together in a stable crystal lattice, requiring a tremendous amount of thermal energy to break these bonds and transition the element from a solid to a liquid state.
5. How does Tungsten's electron configuration explain its various oxidation states?
As a transition metal, Tungsten's ability to exhibit multiple oxidation states is explained by the involvement of its 5d and 6s electrons in chemical bonding. The energy levels of these orbitals are very close, allowing for the loss or sharing of a variable number of electrons. While Tungsten can show oxidation states from -2 to +6, its most common and stable oxidation state is +6. This state is achieved when it loses all six of its valence electrons (four from the 5d orbital and two from the 6s orbital), resulting in a stable electronic arrangement.
6. What makes Tungsten Carbide so hard and why is this property important?
Tungsten carbide (WC) is an interstitial compound, not a simple alloy. Its extreme hardness, which is close to that of a diamond, arises from its unique crystal structure. Small carbon atoms fit into the interstitial spaces of the tungsten metallic lattice, forming a rigid and very strong network with strong covalent characteristics. This structure is highly resistant to deformation and wear. This property is crucial for its main applications in manufacturing cutting tools, drill bits, abrasives, and armour-piercing ammunition, where durability and the ability to cut other hard materials are essential.
7. What are the main uses of pure Tungsten versus Tungsten alloys?
The applications of tungsten vary depending on whether it is in its pure form or as an alloy.
Pure Tungsten: Due to its high melting point and low vapour pressure, pure tungsten is primarily used for applications like filaments in incandescent light bulbs, heating elements in high-temperature furnaces, and electrodes in TIG (Tungsten Inert Gas) welding.
Tungsten Alloys: When alloyed with other metals like steel, cobalt, and nickel, tungsten imparts hardness, strength, and heat resistance. These are known as 'superalloys' and 'high-speed steels', used for making high-performance turbine blades, rocket engine nozzles, and heavy-duty cutting tools.
8. Does Tungsten have any biological role or toxic effects on the environment?
Tungsten is not known to have any essential biological role in humans or animals. The pure metal is considered relatively non-toxic and biologically inert. However, some of its soluble compounds can have mild toxic effects if ingested or inhaled in significant quantities, as they can interfere with the metabolic pathways of other essential elements like molybdenum. Environmentally, concerns have been raised about its use in military applications, as tungsten particles may accumulate in soil and water, but its environmental impact is generally considered lower than that of lead or depleted uranium.
