Element Information
Atomic Numbers 61 through 70

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  This page contains basic information about elements with atomic numbers 61 through 70.  I have tried to make sure the information given here is correct.  However, if you find a mistake, please e-mail me at apurdy@centurytel.net, and I will correct it as soon as possible.

 

Promethium                multicolored.gif (1741 bytes)Click here to return to periodic table                     

Symbol Pm Name Promethium
Atomic Number 61 Atomic Mass (145) amu
Melting Point 1080C Boiling Point 2460C
Protons/Electrons 61 Neutrons 84
Classification Metal State Solid
Density 7.264 g/cm3 Group Lanthanoid
Electronegativity 1.15 Atomic Radius 183 pm
# of Isotopes 0 Color silvery-white
Energy Levels 6 Crystal Structure hexagonal
Proof of the existence of promethium was obtained in 1947 by J.A. Marinsky, L.E. Glendenin, and C.D. Coryell who isolated radioactive isotope promethium-147 from uranium fission products.                                                  

Uses - nuclear battery, convert light to electrical current, thickness gauges

 

Samarium                    multicolored.gif (1741 bytes) Click here to return to periodic table             

Symbol Sm Name Samarium
Atomic Number 62 Atomic Mass 150.350 amu
Melting Point 1072C Boiling Point 1778C
Protons/Electrons 62 Neutrons 88
Classification Metal State Solid
Density 7.537 g/cm3 Group Lanthanoid
Electronegativity 1.17 Atomic Radius 180 pm
# of Isotopes 7 Color silvery-white
Energy Levels 6 Crystal Structure trigonal
Samarium was isolated as an impure oxide and spectroscopically identified as a new element in 1879 by P.-. Lecoq de Boisbaudran.                           

Uses - alloys, headphones, making of permanent magnets, absorber in nuclear reactors

 

Europium                   multicolored.gif (1741 bytes)Click here to return to periodic table                       

Symbol Eu Name Europium
Atomic Number 63 Atomic Mass 151.96 amu
Melting Point 822C Boiling Point 1597C
Protons/Electrons 63 Neutrons 89
Classification Metal State Solid
Density 5.253 g/cm3 Group Lanthanoid
Electronegativity 1.12 Atomic Radius 208 pm
# of Isotopes 2 Color silvery-white
Energy Levels 6 Crystal Structure cubic
Europium was discovered in 1896 by Eugne-Anatole Demaray.   He isolated it into a pure fraction in 1901.

Uses - alloys, color TV phosphor, nuclear control applications

 

Gadolinium                  multicolored.gif (1741 bytes)Click here to return to periodic table                     

Symbol Gd Name Gadolinium
Atomic Number 64 Atomic Mass 157.250 amu
Melting Point 1311C Boiling Point 3233C
Protons/Electrons 64 Neutrons 93
Classification Metal State Solid
Density 7.898 g/cm3 Group Lanthanoid
Electronegativity 1.17 Atomic Radius 180 pm
# of Isotopes 7 Color silvery-white
Energy Levels 6 Crystal Structure hexagonal
J.C.G. Marignac separated gadolinium from the mineral samarskite in 1880, and P.- Lecoq de Boisbaudran obtained a fairly pure sample in 1886.   Both men are given credit for the discovery of gadolinium.                        

Uses - alloys, CD disks

 

Terbium                        multicolored.gif (1741 bytes) Click here to return to periodic table                     

Symbol Tb Name Terbium
Atomic Number 65 Atomic Mass 158.925 amu
Melting Point 1360C Boiling Point 3041C
Protons/Electrons 65 Neutrons 94
Classification Metal State Solid
Density 8.234 g/cm3 Group Lanthanoid
Electronegativity 1.21 Atomic Radius 177 pm
# of Isotopes 1 Color silvery-white
Energy Levels 6 Crystal Structure hexagonal
Terbium was discovered in 1843 by Carl Gustaf Mosander, but its existence was not confirmed for about 30 years.  Pure compounds were not prepared until 1905.                                                        

Uses - aloys, color TV's

 

Dysprosium                  multicolored.gif (1741 bytes) Click here to return to periodic table                  

Symbol Dy Name Dysprosium
Atomic Number 66 Atomic Mass 162.50 amu
Melting Point 1409C Boiling Point 2335C
Protons/Electrons 66 Neutrons 97
Classification Metal State Solid
Density 8.540 g/cm3 Group Lanthanoid
Electronegativity 1.2 Atomic Radius 178 pm
# of Isotopes 7 Color silvery-white
Energy Levels 6 Crystal Structure hexagonal
Dysprosium was first found in 1886 by P.-. Lecoq de Boisbaudran with holmium and other heavy rare earths.  Georges Urbain was able to prepare a resonably pure sample in 1906.              

Uses - alloys, CD disks

 

Holmium                        multicolored.gif (1741 bytes) Click here to return to periodic table                  

Symbol Ho Name Holmium
Atomic Number 67 Atomic Mass 164.930 amu
Melting Point 1470C Boiling Point 2720C
Protons/Electrons 67 Neutrons 98
Classification Metal State Solid
Density 8.781 g/cm3 Group Lanthanoid
Electronegativity 1.23 Atomic Radius 176 pm
# of Isotopes 1 Color silvery-white
Energy Levels 6 Crystal Structure hexagonal
Holmium was discovered in 1878 spectroscopically by J.L. Soret and M. Delafontaine.  It was then discovered independently by Per Teodor Cleve in 1879 when he separated it chemically from erbium and thulium.                      

Uses - alloys

 

Erbium                          multicolored.gif (1741 bytes) Click here to return to periodic table                   

Symbol Er Name Erbium
Atomic Number 68 Atomic Mass 167.26 amu
Melting Point 1522C Boiling Point 2510C
Protons/Electrons 68 Neutrons 99
Classification Metal State Solid
Density 9.045 g/cm3 Group Lanthanoid
Electronegativity 1.24 Atomic Radius 176 pm
# of Isotopes 6 Color silvery-white
Energy Levels 6 Crystal Structure hexagonal
Erbium was discovered in 1843 as an oxide by C.G. Mosander.                        

Uses - alloys, photographic filter, colorant in glasses and porcelain enamel glazes

 

Thulium                        multicolored.gif (1741 bytes) Click here to return to periodic table                 

Symbol Tm Name Thulium
Atomic Number 69 Atomic Mass 168.934 amu
Melting Point 1545C Boiling Point 1727C
Protons/Electrons 69 Neutrons 100
Classification Metal State Solid
Density 9.314 g/cm3 Group Lanthanoid
Electronegativity 1.25 Atomic Radius 176 pm
# of Isotopes 1 Color silvery-white
Energy Levels 6 Crystal Structure hexagonal
Thulium was discovered in 1879 along with holmium by Per Teodor Cleve.     

Uses - alloys, power for portable x-ray machnies

 

Ytterbium                      multicolored.gif (1741 bytes) Click here to return to periodic table                    

Symbol Yb Name Ytterbium
Atomic Number 70 Atomic Mass 173.04 amu
Melting Point 824C Boiling Point 1193C
Protons/Electrons 70 Neutrons 103
Classification Metal State Solid
Density 6.972 g/cm3 Group Lanthanoid
Electronegativity 1.21 Atomic Radius 193 pm
# of Isotopes 7 Color silvery-white
Energy Levels 6 Crystal Structure cubic
The first concentrate of ytterbium was obtained in 1878 by J.C.G. de Marignac.  Georges Urbain and Carl Auer von Welsbach showed in 1907-1908 that what Marignac had found was in fact two elements, now known as ytterbium and lutetium.        

Uses - alloys, metallurgic and chemical experiments, lasers

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