Why Is Ytterbium Important in Chemistry and Modern Technology?
The chemical element ytterbium has the symbol Yb and atomic number 70. It is the fourteenth and penultimate element in the lanthanide sequence, and its +2 oxidation state is the basis for its relative stability. Its most common oxidation state, like that of the other lanthanides, is +3, as seen in its oxide, halides, and other compounds. Soluble ytterbium compounds form complexes with nine water molecules in an aqueous solution, similar to other late lanthanide compounds. Its density, melting, and boiling points vary greatly from those of most other lanthanides due to its closed-shell electron structure.
In 1878, the Swiss chemist Jean Charles Galissard de Marignac isolated an independent component from the rare earth "erbia," which he called "ytterbia" after Ytterby, the Swedish village near where he discovered the new erbium component. He assumed that ytterbia was a compound of ytterbium, a new element he had discovered. This article will study the Physical Properties of Ytterbium, the Chemical Properties of Ytterbium, and the Uses of Ytterbium.
Characteristics of Ytterbium
Physical Properties of Ytterbium
When pure, ytterbium is a smooth, malleable, and ductile chemical element with a bright silvery lustre. It's a rare earth element that dissolves easily in heavy mineral acids. It oxidises slowly in the air and reacts slowly with cold water.
At temperatures above 1.0 kelvin, ytterbium is paramagnetic, unlike the other rare-earth metals, which have antiferromagnetic and/or ferromagnetic properties at low temperatures. The alpha allotrope, on the other hand, is diamagnetic. Ytterbium has the lowest liquid range of all the metals, with a melting point of 824 °C and a boiling point of 1196 °C.
Chemical Properties of Ytterbium
In the presence of sunlight, ytterbium metal tarnishes steadily, acquiring a golden or brown hue. In the presence of oxygen, finely scattered ytterbium readily oxidizes. A luminous emerald-green flame is produced by combining powdered ytterbium with polytetrafluoroethylene or hexachloroethane. Ytterbium reacts with hydrogen to form non-stoichiometric hydrides in a variety of ways. In water, ytterbium dissolves slowly but rapidly in acids, releasing hydrogen gas.
2 Yb (s) + 6 H2O (l) → 2 Yb(OH)3 (aq) + 3 H2 (g)
Ytterbium is an electropositive metal that forms ytterbium(III) hydroxide when it reacts slowly with cold water and rapidly with hot water.
2 Yb (s) + 3 F2 (g) → 2 YbF3 (s) [white]
2 Yb (s) + 3 Cl2 (g) → 2 YbCl3 (s) [white]
Since the ytterbium(III) ion absorbs light in the near-infrared spectrum but not visible light, ytterbia, Yb2O3, is white in colour and ytterbium salts are also colourless. Ytterbium readily dissolves in dilute sulfuric acid, forming solutions containing the colourless Yb(III) ions, which exist as nonahydrate complexes.
Uses of Ytterbium
Source of Gamma Rays
The 169Yb isotope (half-life 32 days) has been used as a radiation source in portable X-ray machines, along with the short-lived 175Yb isotope (half-life 4.2 days) produced by neutron activation during the irradiation of ytterbium in nuclear reactors. The gamma rays released by the source, like X-rays, pass through the body's soft tissues but are blocked by bones and other dense materials.
High-Stability Atomic Clocks
Ytterbium clocks have the highest level of stability, with ticks that are fewer than two sections of one quintillion. Around 10,000 rare-earth atoms are cooled to 10 microkelvins (10 millionths of a degree above absolute zero) and trapped in an optical lattice—a sequence of pancake-shaped wells made of laser light—in the clocks built at the National Institute of Standards and Technology (NIST). Another laser, which "ticks" 518 trillion times a second, causes a change in the atoms' energy levels. The high stability of the clocks is due to a large number of atoms.
Doping of Stainless Steel
Ytterbium can also be used as a dopant in stainless steel to help refine grain refinement, strength, and other mechanical properties. Some ytterbium alloys have only been used in dentistry on a very limited basis.
It's also used in industry as a catalyst.
In dentistry, only a few Ytterbium alloys are used.
Ytterbium is an electropositive silvery-white metal that reacts with water to form ytterbium hydroxide.
Ytterbium is now used in the manufacture of memory devices and tunable lasers.
Did You Know?
Although ytterbium is chemically stable, it is protected from air and moisture by being stored in airtight containers and in an inert environment such as a nitrogen-filled dry box. While studies tend to suggest that the danger is limited, all ytterbium compounds are treated as highly toxic. However, ytterbium compounds irritate the skin and eyes of humans, and some of them may be teratogenic. Metallic ytterbium dust will spontaneously combust, releasing dangerous fumes. Ytterbium fires are impossible to put out with water, and only dry chemical class D fire extinguishers can do so.
FAQs on Ytterbium: Properties, Applications, and Significance
1. What is ytterbium and where is it located in the periodic table?
Ytterbium, with the chemical symbol Yb and atomic number 70, is a soft, silvery-white metallic element. In the periodic table, it is classified as a lanthanoid and is part of the f-block elements, also commonly referred to as the rare-earth elements.
2. What are the main physical properties of ytterbium?
Ytterbium is a bright, lustrous metal known for being highly ductile (can be drawn into wires) and malleable (can be hammered into thin sheets). It exists in three different allotropic forms depending on temperature and pressure. It has a density of 6.90 g/cm³ and a relatively low melting point for a metal at 824°C.
3. What are the most common industrial and scientific applications of ytterbium?
Ytterbium has several important high-tech applications. Its main uses include:
- As a doping agent in fibre optic cables and amplifiers.
- Alloying with stainless steel to enhance grain refinement and strength.
- Its isotope, Yb-169, serves as a radiation source for portable X-ray machines used in non-destructive testing.
- It is also a critical component in developing highly precise atomic clocks.
4. What is the electronic configuration of ytterbium (Yb) according to the NCERT curriculum?
As per the CBSE syllabus, the ground-state electronic configuration for Ytterbium (Yb) is [Xe] 4f¹⁴ 6s². This configuration is particularly important because the 4f subshell is completely filled, which plays a crucial role in the stability of its +2 oxidation state.
5. Is ytterbium a dangerous element to handle?
While solid metallic ytterbium is moderately reactive, its fine dust can be a fire hazard as it may ignite spontaneously in air. Ytterbium compounds are generally considered toxic and can act as irritants to the skin and eyes. Therefore, handling it requires proper safety measures, especially in powdered form.
6. Why does ytterbium exhibit a stable +2 oxidation state, unlike most other lanthanoids that prefer +3?
Ytterbium uniquely shows a stable +2 oxidation state because of its electronic configuration, [Xe] 4f¹⁴ 6s². When it loses its two outer 6s electrons, it achieves a fully-filled 4f¹⁴ subshell. This complete f-orbital provides significant electronic stability, making the Yb²⁺ ion favourable. Most other lanthanoids achieve greater stability by losing three electrons to attain other stable or half-filled configurations.
7. How does ytterbium's electronic structure make it suitable for use in high-power lasers?
The specific energy levels in ytterbium's electron shells make it an excellent gain medium for lasers. Its electrons can efficiently absorb energy from a pump source (like a diode) and then release it as photons at a consistent wavelength. This high efficiency generates minimal waste heat, allowing for the construction of powerful, compact, and reliable ytterbium-doped fibre lasers.
8. What is the key difference between ytterbium (Yb) and yttrium (Y)?
Despite their similar names, ytterbium and yttrium are fundamentally different elements:
- Periodic Table Location: Ytterbium (Yb) is an f-block element (lanthanoid), while Yttrium (Y) is a d-block element (transition metal).
- Electronic Structure: Ytterbium's valence electrons involve the 4f and 6s orbitals, whereas yttrium's involve the 4d and 5s orbitals.
- Properties: Ytterbium is much denser and softer than yttrium. This distinction is a crucial concept in understanding the periodic table.
9. From a chemical properties perspective, why does ytterbium tarnish in air?
Ytterbium tarnishes in the air due to its reactivity with atmospheric oxygen. It is an electropositive metal that slowly oxidises to form a thin, protective layer of ytterbium(III) oxide (Yb₂O₃) on its surface. This layer prevents further, rapid corrosion. It also reacts slowly with cold water and more readily with hot water to produce ytterbium hydroxide and hydrogen gas.
10. What is the real-world significance of using ytterbium isotopes in portable X-ray technology?
The significance lies in creating X-ray sources that are independent of electricity. The isotope ¹⁶⁹Yb emits gamma rays at energies comparable to diagnostic X-rays. As a small, self-contained source, it enables the creation of lightweight, portable devices for non-destructive testing of materials, welds, and structures in remote field locations where a conventional, power-hungry X-ray machine would be impractical.
