70
  Yb  
173.040000
Ytterbium

Name: Ytterbium
Symbol: Yb
Atomic Number: 70
Atomic Weight: 173.040000
Family: Rare Earth Elements
CAS RN: 7440-64-4
Description: A silvery white soft and malleable metal.
State (25C): Solid
Oxidation states: +2, +3

Molar Volume: 24.84 cm3/mole
Valence Electrons: 4f146s2

Boiling Point:  1467K, 1194C, 2181F
Melting Point:
1097K, 824C, 1515F
Electrons Energy Level:  2, 8, 18, 32, 8, 2
Isotopes: 27 + 7 Stable + 6 meta states
Heat of Vaporization:  128.9 kJ/mol
Heat of Fusion: 7.66 kJ/mol
Density:  6.9 g/cm3 @ 300K
Specific Heat:  0.15 J/gK
Atomic Radius: 2.4
Ionic Radius: 0.858
Electronegativity: 1.1 (Pauling); 1.06 (Allrod Rochow)
Vapor Pressure: 395 Pa @ 824C
57
La
138.9
58
Ce
140.1
59
Pr
140.9
60
Nd
144.2
61
Pm
(145)
62
Sm
150.4
63
Eu
152.0
64
Gd
157.3
65
Tb
158.9
66
Dy
162.5
67
Ho
164.9
68
Er
167.3
69
Tm
168.9
70
Yb
173.0
71
Lu
175.0

1s2 2s2p6 3s2p6d10 4s2p6d10f14 5s2p6 6s2

History

The mineral gadolinite, (Ce, La, Nd, Y)2FeBe2Si2O10, discovered in a quarry near the town of Ytterby, Sweden, has been the source of a great number of rare earth elements.  In 1843, Carl Gustaf Mosander, a Swedish chemist, was able to separate gadolinite into three materials, which he named yttria, erbia and terbia.   As might be expected considering the similarities between their names and properties, scientists soon confused erbia and terbia and, by 1877, had reversed their names.  What Mosander called erbia is now called terbia and visa versa. 

In 1878 Jean Charles Galissard de Marignac, a Swiss chemist, discovered that erbia was itself consisted of two components.  He suspected that ytterbia was a compound of a new element he called ytterbium.  Initial identification was tediously made from the same mixture that most chemists of the time worked from: oxides of the lanthanides which gave rise to the term "rare-earth" due to its powdery consistency and often brownish color.  But with the chemical separation techniques available at the time, it was very difficult to distinguish these similar elements.  Even ytterbium itself turned out to hide another element. One component was named ytterbia by Marignac while the other component retained the name erbia.  Marignac believed that ytterbia was a compound of a new element, which he named ytterbium.  Other chemists produced and experimented with ytterbium in an attempt to determine some of it's properties.  Unfortunately, different scientists obtained different results from the same experiments. 

While some scientists believed that these inconsistent results were caused by poor procedures or faulty equipment, Georges Urbain, a French chemist, believed that ytterbium wasn't an element at all, but a mixture of two elements.  I n 1907, Urbain was able to separate ytterbium into two elements.  Urbain named one of the elements neoytterbium (new ytterbium) and the other element lutecium.  Chemists eventually changed the name neoytterbium back to ytterbium and changed the spelling of lutecium to lutetium.  Due to his original belief of the composition of ytterbia, Marignac is credited with the discovery of ytterbium.  Even ytterbium itself turned out to hide another element.

Austrian mineralogist Baron Carl 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.

Characteristics

Ytterbium is a soft, malleable and rather ductile element that exhibits a bright silvery lister.  A rare earth element, it is easily attacked and dissolved by mineral acids, slowly reacts with water, and oxidizes in air.  Mostly obtained from monazite sand, ytterbium makes up about 0.03% of that mixture.

1s2
2s2 2p6
3s2 3p6 3d10
4s2 4p6 4d10 4f14
5s2 5p6
6s2

Ytterbium has three allotropes which are called alpha, beta and gamma and whose transformation points are at -13C 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 resistance is tenfold larger at about 39,000 atm (3.9 GPa) but then dramatically drops to around 10% of its room temperature resistivity value at 40,000 atm (4 GPa).

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.

Applications

One ytterbium isotope has been used as a radiation source substitute for a portable X-ray machine when electricity was not available.  Its metal could also be used to help improve the grain refinement, strength, and can be alloyed with stainless steel to improve some of its mechanical properties and used as a doping agent in fiber optic cable where it can be used as an amplifier.  Some ytterbium alloys have been used in dentistry.  here are few other uses of this element, e.g. in the form of ions in active laser media.

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 (31.8% 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 6 meta states, with the most stable being Yb-169m (t 46 seconds).

The isotopes of ytterbium range in atomic weight from 147.96742 amu (148Yb) to 180.95615 amu (181Yb).  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 thulium-69 isotopes, and the primary products after are element lutetium-71 isotopes.  Of interest to modern quantum optics, the different ytterbium isotopes follow either Bose-Einstein statistics or Fermi-Dirac statistics, leading to interesting behavior in optical lattices.

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Isotope  
Atomic Mass
 
Half-Life
148Yb 147.96742 ~250 ms
149Yb 148.96404 0.7 seconds
150Yb 149.95842 ~700 ms
151Yb 150.95540 1.6 seconds
151m1Yb   1.6 seconds
152Yb 151.95029 3.04 seconds
153Yb 152.94948 4.2 seconds
154Yb 153.946394 0.409 seconds
155Yb 154.945782 1.793 seconds
156Yb 155.942818 26.1 seconds
157Yb 156.942628 38.6 seconds
158Yb 157.939866 1.49 minutes
159Yb 158.94005 1.67 minutes
160Yb 159.937552 4.8 minutes
161Yb 160.937902 4.2 minutes
162Yb 161.935768 18.87 minutes
163Yb 162.936334 11.05 minutes
164Yb 163.934489 75.8 minutes
165Yb 164.93528 9.9 minutes
166Yb 165.933882 56.7 hours
167Yb 166.934950 17.5 minutes
168Yb 167.933897 Stable
169Yb 168.935190 32.026 days
169mYb   46 seconds
170Yb 169.9347618 Stable
171Yb 170.9363258 Stable
172Yb 171.9363815 Stable
173Yb 172.9382108 Stable
174Yb 173.9388621 Stable
175Yb 174.9412765 4.185 days
176Yb 175.9425717 Stable
176mYb   11.4 seconds
177Yb 176.9452608 1.911 hours
177mYb   6.41 seconds
178Yb 177.946647 74 minutes
179Yb 178.95017 8.0 minutes
180Yb 179.95233 2.4 minutes
181Yb 180.95615 ~1 minutes

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.

atom.gif (700 bytes)

Ytterbium Data

 

Atomic Structure

Atomic Radius (): 2.4
Atomic Volume cm3/mol : 24.79cm3/mol
Covalent Radius: 1.74
Crystal Structure: Cubic face centered
Ionic Radius: 0.858

Chemical Properties

Electrochemical Equivalents: 2.152g/amp-hr
Electron Work Function: unknown
Electronegativity: 1.1 (Pauling); 1.06 (Allrod Rochow)
Heat of Fusion: 7.66kJ/mol
First Ionization Potential: 6.254
Second Ionization Potential: 12.188
Third Ionization Potential: 25.03
Valence Electron Potential (-eV): 50.3
Ionization Energy (eV): 6.254 eV

Physical Properties

Atomic Mass Average: 173.04
Boiling Point: 1467K, 1194C, 2181F
Melting Point: 1097K, 824C, 1515F
Heat of Vaporization: 128.9 kJ/mol
Coefficient of Lineal Thermal Expansion/K-1: 25E-6
Electrical Conductivity: 0.0351 106/cm
Thermal Conductivity: 0.349 W/cmK
Density: 6.9 g/cm3 @ 300K
Enthalpy of Atomization: 180 kJ/mole @ 25C
Enthalpy of Fusion: 7.66 kJ/mole
Enthalpy of Vaporization: 128.9 kJ/mole
Molar Volume: 24.84 cm3/mole
Specific Heat: 0.15 J/gK
Vapor Pressure: 395 Pa @ 824C
Estimated Crustal Abundance: 3.2 milligrams per kilogram
Estimated Oceanic Abundance: 8.210-7 milligrams per liter