Ytterbium was discovered in 1878. It oxidizes in the air but it forms a protective layer on the surface. 160Yb is used in portable X-ray machines that need no electricity. It is used as a catalyst in organic chemical industry.
History and Discovery
Ytterbium was discovered by Jean Charles Galissard de Marignac in 1878. He was analyzing the samples of gadolinite when he found new element and named it ytterbia after Ytterby the Swedish village. He also heated erbium nitrate until decomposed and named the resultant white powder ytterbium oxide. In 1907, Georges Urbain separated ytterbia into two components neoytterbia and lutecia. Neoytterbia later called ytterbium and lutecia was known as lutetium. In the same time, Carl Auer von Welsbach independently carried out research, but he called new element aldebaranium and cassiopeium. In 1937, first ytterbium metal was made by Klemm and Bonner by heating ytterbium chloride and potassium together. Its pure metal form was manufactured in 1953 by A. Daane, David Dennison and Frank Spedding [1].
Ytterbium
| Periodic Table Classification | Group n/a Period 6 |
|---|---|
| State at 20C | Solid |
| Color | Silvery white |
| Electron Configuration | [Xe] 4f14 6s2 |
| Electron Number | 70 |
| Proton Number | 70 |
| Electron Shell | 2, 8, 18, 32, 8, 2 |
| Density | 6.90 g.cm-3 at 20°C |
| Atomic number | 70 |
| Atomic Mass | 173.04 g.mol -1 |
| Electronegativity according to Pauling | 1.10 |
Occurrence
Ytterbium abundance in earth crust is about 3 mg/kg. It is not found free in nature. Ytterbium is present along with several rare minerals. It is common substitute to yttrium minerals. It is also found in euxenite and xenotime (phosphate mineral). Ytterbium is mostly separated from its ores through ion exchange and solvent extraction technique otherwise it is very difficult [2]. The main deposits of ytterbium are found in China, United States, Brazil, India, Sri Lanka and Australia.
Physical Characteristics
Ytterbium displays bright silver luster, it is soft, pliable and undergo soft deformation (ductile). It has three allotropes forms: alpha, beta and gamma. They undergo deformation but depends on pressure and stress at temperature about -13OC and 795OC. Ytterbium is paramagnetic at 1.0 K. It usually have antiferromagnetic and ferromagnetic properties at low temperatures [3]. Ytterbium has chemical symbol Yb with atomic number 70. Its atomic weight is 173.045. Ytterbium melting point is 824OC and boiling point is 1196OC. Its density near room temperature is about 6.90 g/cm3.
Chemical Characteristics
Ytterbium is tarnished in air slowly. It oxidizes in air when finely dispersed. Ytterbium burns in powder mixture with hexachloroethane and produce luminous emerald green flame. It reacts with hydrogen and forms non-stoichiometric hydrides. It also dissolves slowly in water but quickly in acid and liberate hydrogen gas. Ytterbium is electropositive react slowly quite quickly with hot water and formed ytterbium (lll) hydroxide. It reacts with all halogens and form dihalides and trihalides. Yb2O3 is in white color and the salts are also colorless. Ytterbium mostly exist in +2 and +3 oxidation states. Ytterbium (ll) ions are strong reducing agent and decomposes water to release hydrogen gas.
Significance and Uses
- 169Yb isotope along with 175Yb was used as a radiation source in portable X-ray machine.
- 169Yb is used in nuclear medicine.
- Ytterbium is also present in high stability atomic clocks.
- It is used as dopant to improve the grain refinement, strength and other mechanical properties of stainless steel.
- In alloy form it is used in dentistry.
- Ytterbium (lll) ion used as doping material in active laser media, solid state lasers and double clad fiber laser.
- Ytterbium metal increases electrical resistivity so it is used to monitor ground deformation from earth quakes and explosions.
- It is also act as industrial catalyst.
- It can be used to dope phosphorous or for ceramic capacitors.
- It is also used with yttrium in certain steel alloys.
Health Effects
Ytterbium in pure form is non-toxic. It can sometime cause skin and eye irritation. However, its salts and certain compounds are highly toxic. Ytterbium compounds should be stored in closed container and must be protected from moisture and direct contact with air. Ytterbium salts, in minute quantity have been reported to stimulate metabolism otherwise it has no biological role.
Isotopes of Ytterbium
Ytterbium has seven stable isotopes: 168Yb, 170Yb, 171Yb, 172Yb, 173Yb, 174Yb and 176Yb. It has twenty seven radioisotopes in which the most stable one is 169Yb have half-life of 32 days. 175Yb with the half-life of 4.18 days. 166Yb have 56.7 hours. All remaining have half-lives less than two hours and some have less than 20 minutes. Ytterbium isotopes atomic weight range from 148Yb to 181Yb.
REFERENCES
[1]. https://en.wikipedia.org/wiki/Ytterbium
[2]. https://www.chemicool.com/elements/ytterbium.html
[3]. Hammond, C. R. (2000). The Elements, in Handbook of Chemistry and Physics(81st ed.). CRC press. ISBN 978-0-8493-0481-1