Symbol	Lu
Atomic number	71
Group	-
Period	6
Block	f
Classification	Lanthanide

Appearance	Silvery white
Color	Silver

Number of protons	71 p+
Number of neutrons	104 n0
Number of electrons	71 e-

From Wikipedia, the free encyclopediaLutetium is a chemical element with symbol Lu and atomic number 71. It is a silvery white metal, which resists corrosion in dry, but not in moist air. It is considered the first element of the 6th-period transition metals and the last element in the lanthanide series, and is traditionally counted among the rare earths.

Phase at STP	Solid
Density	9.841 g/cm3
Atomic weight	174.967 u

Melting point	1925 K 1651.85 °C 3005.33 °F
Boiling point	3675 K 3401.85 °C 6155.33 °F
Heat of vaporization	355 kJ/mol

Electronegativity (Pauling Scale)	1.27
Electron affinity	33.4 kJ/mol
Oxidation states	0, +1, +2, +3 (a weakly basic oxide)
Ionization energies	523.5 kJ/mol 1340 kJ/mol 2022.3 kJ/mol 4370 kJ/mol 6445 kJ/mol

Electron configuration Shorthand configuration	[Xe] 4f14 5d1 6s2
Electron configuration Full configuration	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d1 6s2
Electron configuration chart	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d1 6s2
Electrons per shell	2, 8, 18, 32, 9, 2
Valence electrons	2
Valency electrons	3
Bohr model	Figure: Shell diagram of Lutetium (Lu) atom.
Orbital Diagram 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 6s

Discovery	Carl Auer von Welsbach, Georges Urbain (1906)
First isolation	Carl Auer von Welsbach (1906)
Named by	Georges Urbain (1906)
Discovery of lutetium Lutetium was independently discovered in 1907 by French scientist Georges Urbain, Austrian mineralogist Baron Carl Auer von Welsbach, and American chemist Charles James. All of these researchers found lutetium as an impurity in the mineral ytterbia, which was previously thought to consist entirely of ytterbium. The dispute on the priority of the discovery occurred shortly after, with Urbain and Welsbach accusing each other of publishing results influenced by the published research of the other; the naming honor went to Urbain, as he had published his results earlier. He chose the name lutecium for the new element, but in 1949 the spelling was changed to lutetium. In 1909, the priority was finally granted to Urbain and his names were adopted as official ones; however, the name cassiopeium (or later cassiopium) for element 71 proposed by Welsbach was used by many German scientists until the 1950s.

CAS Number	7439-94-3
ChemSpider ID	22371
EC number	231-103-0
PubChem CID Number	23929