Ytterbium

2008/9 Schools Wikipedia Selection. Related subjects: Chemical elements

70 thulium ← ytterbium → lutetium - ↑ Yb ↓ No Periodic Table - Extended Periodic Table
General
Name, Symbol, Number	ytterbium, Yb, 70
Chemical series	lanthanides
Group, Period, Block	n/a, 6, f
Appearance	silvery white
Standard atomic weight	173.04 (3)  g·mol−1
Electron configuration	[Xe] 4f14 6s2
Electrons per shell	2, 8, 18, 32, 8, 2
Physical properties
Phase	solid
Density (near r.t.)	6.90  g·cm−3
Liquid density at m.p.	6.21  g·cm−3
Melting point	1097  K (824 ° C, 1515 ° F)
Boiling point	1469  K (1196 ° C, 2185 ° F)
Heat of fusion	7.66   kJ·mol−1
Heat of vaporization	159   kJ·mol−1
Specific heat capacity	(25 °C) 26.74  J·mol−1·K−1
Vapor pressure P(Pa) 1 10 100 1 k 10 k 100 k at T(K) 736 813 910 1047 (1266) (1465)
Atomic properties
Crystal structure	cubic face centered
Oxidation states	2,3 ( basic oxide)
Electronegativity	? 1.1 (Pauling scale)
Ionization energies ( more)	1st:  603.4   kJ·mol−1
	2nd:  1174.8  kJ·mol−1
	3rd:  2417  kJ·mol−1
Atomic radius	175   pm
Atomic radius (calc.)	222  pm
Miscellaneous
Magnetic ordering	no data
Electrical resistivity	( r.t.) (β, poly) 0.250 µΩ·m
Thermal conductivity	(300 K) 38.5  W·m−1·K−1
Thermal expansion	( r.t.) (β, poly) 26.3 µm/(m·K)
Speed of sound (thin rod)	(20 °C) 1590 m/s
Young's modulus	(β form) 23.9  GPa
Shear modulus	(β form) 9.9  GPa
Bulk modulus	(β form) 30.5  GPa
Poisson ratio	(β form) 0.207
Vickers hardness	206  MPa
Brinell hardness	343  MPa
CAS registry number	7440-64-4
Selected isotopes
Main article: Isotopes of ytterbium iso NA half-life DM DE ( MeV) DP 166Yb syn 56.7 h ε 0.304 166Tm 168Yb 0.13% 168Yb is stable with 98 neutrons 169Yb syn 32.026 d ε 0.909 169Tm 170Yb 3.04% 170Yb is stable with 100 neutrons 171Yb 14.28% 171Yb is stable with 101 neutrons 172Yb 21.83% 172Yb is stable with 102 neutrons 173Yb 16.13% 173Yb is stable with 103 neutrons 174Yb 31.83% 174Yb is stable with 104 neutrons 175Yb syn 4.185 d β- 0.470 175Lu 176Yb 12.76% 176Yb is stable with 106 neutrons 177Yb syn 1.911 h β- 1.399 177Lu
References

Ytterbium (pronounced /ɪˈtɝbiəm/) is a chemical element with the symbol Yb and atomic number 70. A soft silvery metallic element, ytterbium is a rare earth of the lanthanide series and is found in the minerals gadolinite, monazite, and xenotime. The element is sometimes associated with yttrium or other related elements and is used in certain steels. Natural ytterbium is a mix of seven stable isotopes.

Notable characteristics

Ytterbium is a soft, malleable and rather ductile element that exhibits a bright silvery luster. A rare earth element, it is easily attacked and dissolved by mineral acids, slowly reacts with water, and oxidizes in air.

Ytterbium has three allotropes which are called alpha, beta and gamma and whose transformation points are at −13 ° C and 795 °C. The beta form exists at room temperature and has a face-centered crystal structure while the high-temperature gamma form has a body-centered crystal structure.

Normally, the beta form has a metallic-like electrical conductivity, but becomes a semiconductor when exposed to around 16,000 atm (1.6 GPa). Its electrical resistivity is tenfold larger at about 39,000 atm (3.9 GPa) but then drops dramatically, to around 10% of its room temperature resistivity value, at 40,000 atm (4 GPa).

Ytterbium is one of the lanthanides that is able to become divalent. Like the other potentially divalent lanthanides, samarium and europium, it is capable of being extracted into mercury by the use of sodium amalgam, which made it one of the easier lanthanides to purify using classical techniques. However, this divalency was not discovered until the 20th century.

Applications

Usually, very small amount of Yb is used; either small sample of radioactive isotope as source of X-rays, or small concentration dopant.

Doping of stainless steel

Ytterbium could also be used to help improve the grain refinement, strength, and other mechanical properties of stainless steel. Some ytterbium alloys have been used in dentistry.

Solar cells

Ytterbium has a single absorption band at 985 nanometers, which is used to convert infrared energy into electricity in solar cells.

History

Ytterbium was discovered by the Swiss chemist Jean Charles Galissard de Marignac in 1878. Marignac found a new component in the earth then known as erbia and named it ytterbia (after Ytterby, the Swedish town where he found the new erbia component). He suspected that ytterbia was a compound of a new element he called ytterbium.

In 1907, the French chemist Georges Urbain separated Marignac's ytterbia into two components, neoytterbia and lutecia. Neoytterbia would later become known as the element ytterbium and lutecia would later be known as the element lutetium. Auer von Welsbach independently isolated these elements from ytterbia at about the same time but called them aldebaranium and cassiopeium.

The chemical and physical properties of ytterbium could not be determined until 1953 when the first nearly pure ytterbium was produced.

Occurrence

Ytterbium is found with other rare earth elements in several rare minerals. It is most often recovered commercially from monazite sand (0.03% ytterbium). The element is also found in euxenite and xenotime. Ytterbium is normally difficult to separate from other rare earths but ion-exchange and solvent extraction techniques developed in the late 20th century have simplified separation. Known compounds of ytterbium are rare—they haven't been well characterized yet.

Isotopes

Naturally occurring ytterbium is composed of 7 stable isotopes, Yb-168, Yb-170, Yb-171, Yb-172, Yb-173, Yb-174, and Yb-176, with Yb-174 being the most abundant (31.83% natural abundance). 27 radioisotopes have been characterized, with the most stable being Yb-169 with a half-life of 32.026 days, Yb-175 with a half-life of 4.185 days, and Yb-166 with a half life of 56.7 hours. All of the remaining radioactive isotopes have half-lifes that are less than 2 hours, and the majority of these have half lifes that are less than 20 minutes. This element also has 12 meta states, with the most stable being Yb-169m (t_½ 46 seconds).

The isotopes of ytterbium range in atomic weight from 147.9674 u (Yb-148) to 180.9562 u (Yb-181). The primary decay mode before the most abundant stable isotope, Yb-174 is electron capture, and the primary mode after is beta emission. The primary decay products before Yb-174 are element 69 (thulium) isotopes, and the primary products after are element 71 (lutetium) isotopes. Of interest to modern quantum optics, the different ytterbium isotopes follow either Bose-Einstein statistics or Fermi-Dirac statistics, leading to interesting behaviour in optical lattices.

Precautions

Although ytterbium is fairly stable, it nevertheless should be stored in closed containers to protect it from air and moisture. All compounds of ytterbium should be treated as highly toxic although initial studies appear to indicate that the danger is limited. Ytterbium compounds are, however, known to cause skin and eye irritation and may be teratogenic. Metallic ytterbium dust poses a fire and explosion hazard.

Compounds

• Halides: YCl₂, YBr₃, YCl₃, YF₃
• Oxides: Y₂O₃