Science Fair Project Encyclopedia
|Name, Symbol, Number||Ytterbium, Yb, 70|
|Group, Period, Block||NA, 6, f|
|Density, Hardness||6570 kg/m3, ND|
|Appearance|| silvery white|
|Atomic weight||173.04 u|
|Atomic radius (calc.)||175 (222) pm|
|Covalent radius||ND pm|
|van der Waals radius||ND pm|
|e- 's per energy level||2,8,18,32,8,2|
|Oxidation states (Oxide)||3 (base)|
|Crystal structure||Cubic face centered|
|State of matter||solid|
|Melting point||1097 K (1515 °F)|
|Boiling point||1467 K (2181 °F)|
|Molar volume||24.84 ×10-6 m3/mol|
|Heat of vaporization||128.9 kJ/mol|
|Heat of fusion||7.66 kJ/mol|
|Velocity of sound||1590 m/s at 293.15 K|
|Electronegativity||1.1 (Pauling scale)|
|Specific heat capacity||150 J/(kg*K)|
|Electrical conductivity||3.51 106/m ohm|
|Thermal conductivity||34.9 W/(m*K)|
|1st ionization potential||603.4 kJ/mol|
|2nd ionization potential||1174.8 kJ/mol|
|3rd ionization potential||2417 kJ/mol|
|4th ionization potential||4203 kJ/mol|
|Most stable isotopes|
|SI units & STP are used except where noted.|
Ytterbium is a chemical element in the periodic table that has 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.
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. Its electrical resistance is tenfold larger at about 39,000 atm but then dramatically drops to around 10% of its room temperature resistivity value at 40,000 atm.
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 other mechanical properties of stainless steel. Some ytterbium alloys have been used in dentistry. There are few other uses of this element, e.g. in the form of ions in active laser media.
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 (which was in fact the first rare earth to be discovered).
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.
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. Compounds of ytterbium are rare.
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). 22 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 (t½ 46 seconds).
The isotopes of ytterbium range in atomic weight from 150.955 u (Yb-151) to 179.952 u (Yb-180). 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.
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.
- Los Alamos National Laboratory – Ytterbium
- Guide to the Elements – Revised Edition, Albert Stwertka, (Oxford University Press; 1998) ISBN 0-19-508083-1
- It's Elemental – Ytterbium
- WebElements.com – Ytterbium (also used as a reference)
- EnvironmentalChemistry.com – Ytterbium (also used as a reference)
- High-res. pictures and details about ytterbium metal (German / English)
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details