Yttrium

Yttrium, ₃₉Y
Yttrium
Pronunciation	/ˈɪtriəm/ (IT-ree-əm)
Appearance	silvery white
Standard atomic weight Ar°(Y)
	88.905838±0.000002; 88.906±0.001 (abridged);
Yttrium in the periodic table
	strontium ← yttrium → zirconium
Atomic number (Z)	39
Group	group 3
Period	period 5
Block	d-block
Electron configuration	[Kr] 4d1 5s2
Electrons per shell	2, 8, 18, 9, 2
Physical properties
Phase at STP	solid
Melting point	1799 K (1526 °C, 2779 °F)
Boiling point	3203 K (2930 °C, 5306 °F)
Density (near r.t.)	4.472 g/cm3
when liquid (at m.p.)	4.24 g/cm3
Heat of fusion	11.42 kJ/mol
Heat of vaporization	363 kJ/mol
Molar heat capacity	26.53 J/(mol·K)
Atomic properties
Oxidation states	0, +1, +2, +3 (a weakly basic oxide)
Electronegativity	Pauling scale: 1.22
Ionization energies	1st: 600 kJ/mol ; 2nd: 1180 kJ/mol ; 3rd: 1980 kJ/mol ; ;
Atomic radius	empirical: 180 pm
Covalent radius	190±7 pm
	Spectral lines of yttrium
Other properties
Natural occurrence	primordial
Crystal structure	hexagonal close-packed (hcp)
Thermal expansion	α, poly: 10.6 µm/(m⋅K) (at r.t.)
Thermal conductivity	17.2 W/(m⋅K)
Electrical resistivity	α, poly: 596 nΩ⋅m (at r.t.)
Magnetic ordering	paramagnetic
Molar magnetic susceptibility	+2.15×10−6 cm3/mol (2928 K)
Young's modulus	63.5 GPa
Shear modulus	25.6 GPa
Bulk modulus	41.2 GPa
Speed of sound thin rod	3300 m/s (at 20 °C)
Poisson ratio	0.243
Brinell hardness	200–589 MPa
CAS Number	7440-65-5
History
Naming	after Ytterby (Sweden) and its mineral ytterbite (gadolinite)
Discovery	Johan Gadolin (1794)
First isolation	Friedrich Wöhler (1838)
Isotopes of yttrium
γ	–
γ	–
γ	–
γ	–

Yttrium is a chemical element; it has symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element". Yttrium is almost always found in combination with lanthanide elements in rare-earth minerals and is never found in nature as a free element. ⁸⁹Y is the only stable isotope and the only isotope found in the Earth's crust.

The most important present-day use of yttrium is as a component of phosphors, especially those used in LEDs. Historically, it was once widely used in the red phosphors in television set cathode ray tube displays. Yttrium is also used in the production of electrodes, electrolytes, electronic filters, lasers, superconductors, various medical applications, and tracing various materials to enhance their properties.

Yttrium has no known biological role. Exposure to yttrium compounds can cause lung disease in humans.

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.