Key Characteristics and Real-World Applications of Terbium
What is Terbium?
Terbium is the f-block element. Its atomic number is 65. It is present in the sixth period. The symbol of terbium is Tb. Tb element is silver-white in colour. Terbium electron configuration is [Xe]4f96S2. The electronic configuration of Tb shows that it is the f-block element, as the last electron enters into the f-subshell.
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Properties of Terbium
Terbium is a silver-white element.
It occurs in the solid-state at standard temperature and pressure.
It’s melting point is 1629 K.
Its boiling point is 3396 K.
Its density is 8.23 g/cm3.
Its heat of fusion is 10.15 kJ/mol.
Its heat of vaporization is 391 KJ/mol.
Its molar heat capacity is 28.91 J/mol.K.
It shows five oxidation states: 0, +1, +2, +3, +4.
It is soft, malleable, and ductile in nature.
Below 219 K temperature, it possesses ferromagnetic properties and above 219 K temperature, it possesses antiferromagnetic properties.
Terbium being electropositive in nature oxidises when reacts with an acid.
2 Tb (s) + 3 H2SO4 → 2 Tb3+ + 3 SO2−4 + 3 H2↑
It gets oxidised in the presence of air and forms terbium oxide.
8Tb + 7O2 → 2Tb4O7
Uses of Terbium
Terbium is used as a doping agent in different chemicals like calcium fluoride, strontium molybdate, and calcium tungstate for making solid-state devices.
Terbium is used in making alloys.
Terbium is used in electrical devices.
Its oxide is used in making fluorescent devices.
It is used in detecting endospores.
Harmful Effects of Terbium
It acts as an irritant when coming in contact with eyes and skin.
It is mildly toxic in nature. So, it causes harmful effects in the body when ingested.
Did You Know?
Terbium is an element which never occurs in free form in nature.
Important ores of terbium are manazite, bastnasite, and cerite.
India is one of the main mining areas of terbium.
FAQs on Terbium: Properties, Uses, and Safety in Chemistry
1. What is Terbium (Tb)?
Terbium, with the symbol Tb, is a chemical element with an atomic number of 65. It is a silvery-white, rare earth metal belonging to the lanthanide series of the periodic table. Terbium is known for being malleable, ductile, and soft enough to be cut with a knife. It is reasonably stable in air but is primarily valued for its unique fluorescent properties.
2. What are the key physical and chemical properties of Terbium?
Terbium exhibits several distinct properties characteristic of a lanthanide metal. Key properties include:
- Appearance: A bright, silvery-white metal.
- Physical State: Solid at standard temperature and pressure (298K).
- Malleability and Ductility: It is both malleable (can be hammered into sheets) and ductile (can be drawn into wires).
- Reactivity: Terbium slowly oxidises in air and reacts with cold water. It is more reactive than many other rare earth metals.
- Magnetic Properties: It is paramagnetic at room temperature and becomes ferromagnetic at temperatures below 219 K.
- Common Oxidation State: The most stable oxidation state is +3, although a +4 state can also exist.
3. What are the most important uses and applications of Terbium?
The unique properties of Terbium make it valuable in several high-tech applications. Its most important uses include:
- Phosphors and Lighting: Terbium compounds are used to create the green phosphor in trichromatic lighting, low-energy lightbulbs, and CRT screens.
- Solid-State Devices: It is used as a dopant in materials like calcium fluoride and strontium molybdate for use in solid-state electronics.
- Magnets: An alloy of terbium, iron, and dysprosium known as Terfenol-D is used in actuators, sensors, and other magnetomechanical devices due to its strong magnetostrictive properties.
- Medical Imaging: It helps improve the safety of medical X-rays by enabling high-quality images with shorter exposure times.
4. Where is Terbium found in nature?
Terbium is not found as a free element in nature. It is contained within various minerals, often alongside other rare earth elements. The primary commercial sources of terbium are the minerals monazite, xenotime, and bastnäsite. It is extracted from these minerals through complex ion exchange and solvent extraction processes.
5. What is the electron configuration of Terbium and why is it significant?
The electron configuration of Terbium (Tb) is [Xe] 4f⁹ 6s². This configuration is significant because the partially filled 4f orbital is responsible for Terbium's most interesting properties. The electrons in this orbital lead to its strong paramagnetic behaviour and, more importantly, its characteristic green fluorescence. The tendency to lose the 6s² and one 4f electron explains its stable +3 oxidation state (Tb³⁺), which is common across the lanthanide series.
6. Is Terbium considered a safe element to handle?
Terbium metal in its bulk form is considered to have low toxicity and poses little risk. However, like other rare earth metals, its compounds should be handled with standard laboratory precautions. Inhaling terbium dust or fumes can cause irritation. There is currently no evidence that terbium plays any biological role in the human body.
7. Why does Terbium exhibit a brilliant green fluorescence?
Terbium's strong green fluorescence is a result of the electronic transitions within the Tb³⁺ ion. When these ions are excited, typically by ultraviolet (UV) light, their electrons jump to higher energy levels. As they fall back to their ground state, they release this energy as photons of a specific wavelength, which falls in the green part of the visible spectrum (around 546 nm). This highly efficient and stable emission makes terbium essential for creating green phosphors in lighting and display technologies.
8. How does Terbium's position in the f-block affect its properties compared to d-block elements?
As an f-block element, Terbium's properties are primarily determined by its 4f electrons, which are shielded by the outer 5s and 5p orbitals. This shielding results in very similar chemical properties among all lanthanides, dominated by the +3 oxidation state. In contrast, d-block elements (transition metals) use their d-orbitals as valence electrons, leading to a wide variety of oxidation states and more diverse chemical behaviours (e.g., Manganese can have oxidation states from +2 to +7).
