Element Information
Atomic Numbers 81 through 90

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   This page contains basic information about the elements with atomic numbers 81 through 90.  I have tried to make sure the information 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.

 

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

Symbol Tl Name Thallium
Atomic Number 81 Atomic Mass 204.38 amu
Melting Point 303.5C Boiling Point 1457C
Protons/Electrons 81 Neutrons 123
Classification Other Metal State Solid
Density 11.85 g/cm3 Specific Heat 6 / 13
Electronegativity 1.83 Atomic Radius 170 pm
# of Isotopes 2 Color bluish-gray
Energy Levels 6 Crystal Structure hexagonal
Sir William Crookes discovered thallium in 1861.  Crookes presumed the element was sulfur-like,but in 1862, he and Claude-Auguste Lamy independently isolated thallium. They found it to be a metal unlike the elements in the group containing sulfur.                                                      

Uses - IR detectors, photocells, rat and ant poison

 

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

Symbol Pb Name Lead
Atomic Number 82 Atomic Mass 207.19 amu
Melting Point 327.5C Boiling Point 1744C
Protons/Electrons 82 Neutrons 125
Classification Other Metal State Solid
Density 11.29 g/cm3 Period/Group 6 / 14
Electronegativity 2.1 Atomic Radius 146 pm
# of Isotopes 4 Color gray
Energy Levels 6 Crystal Structure cubic
Lead was known in ancient times, and the alchemists of old believed it to be the oldest of all metals.                           

Uses - batteries, solder, paints, shielding against radiation, sound absorber, used by the Romans for plumbing

 

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

Symbol Bi Name Bismuth
Atomic Number 83 Atomic Mass 208.9806 amu
Melting Point 271.3C Boiling Point 1560C
Protons/Electrons 83 Neutrons 126
Classification Other Metal State Solid
Density 9.747 g/cm3 Period/Group 6 / 15
Electronegativity 2.02 Atomic Radius 150 pm
# of Isotopes 1 Color white
Energy Levels 6 Crystal Structure rhombohedral
Bismuth was described by a German monk, Basil Valentine, in 1450.            

Uses -  antacid, fusible alloy, pharmaceuticals, fuses, production of malleable irons, catalyst for making acrylic fibers, cosmetics

 

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

Symbol Po Name Polonium
Atomic Number 84 Atomic Mass (209) amu
Melting Point 254C Boiling Point 962C
Protons/Electrons 84 Neutrons 125
Classification Other Metal State Solid
Density 9.4 g/cm3 Specific Heat 6 / 16
Electronegativity 2 Atomic Radius 168 pm
# of Isotopes 1 Color blue
Energy Levels 6 Crystal Structure cubic
Polonium was discovered in 1898 by Pierre and Marie Curie.                          

Uses -   thermoelectric power, source of neutrons, elimination of static charges in textile mills

 

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

Symbol At Name Astatine
Atomic Number 85 Atomic Mass (210) amu
Melting Point 302C Boiling Point 337C
Protons/Electrons 85 Neutrons 125
Classification Metalloid State Solid
Density no data Period/Group 6 / 17
Electronegativity 2.2 Atomic Radius 127 pm
# of Isotopes 0 Color no data
Energy Levels 6 Crystal Structure no data
Astatine was first synthetically produced in 1940 at the University of California by Dale R. Corson, K.R. MacKenzie, and Emilio Segr, who bombarded bismuth with accelerated alpha particles to yield astatine and neutrons.                                                  

Uses -  no uses known

 

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

Symbol Rn Name Radon
Atomic Number 86 Atomic Mass (222) amu
Melting Point - 71C Boiling Point - 62C
Protons/Electrons 86 Neutrons 136
Classification Noble Gas State Gas
Density 0.00973 g/cm3 Period/Group 6 / 18
Electronegativity NA Atomic Radius 120 pm
# of Isotopes 0 Color colorless
Energy Levels 6 Crystal Structure cubic
The longest lived isotope, radon-222, was discovered in 1900 by the German chemist, Friedrich E. Dorn.                   

Uses - earthquake prediction, treatment of cancer

 

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

Symbol Fr Name Francium
Atomic Number 87 Atomic Mass (223) amu
Melting Point 27.2C Boiling Point 677C
Protons/Electrons 87 Neutrons 136
Classification Alkali Metal State Solid
Density 1.87 g/cm3 Period/Group 7 / 1
Electronegativity 0.7 Atomic Radius no data
# of Isotopes 1 Color no data
Energy Levels 7 Crystal Structure cubic
Francium was discovered by Marguerite Perey in 1939.                                         

Uses -  no uses known

 

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

Symbol Ra Name Radium
Atomic Number 88 Atomic Mass (226) amu
Melting Point ~700C Boiling Point ~ 1737C
Protons/Electrons 88 Neutrons 138
Classification Alkaline Earth Metal State Solid
Density ~ 5 g/cm3 Period/Group 7 / 2
Electronegativity 0.9 Atomic Radius 215 pm
# of Isotopes 4 Color white
Energy Levels 7 Crystal Structure cubic
Radium was discovered in 1898 by Pierre and Marie Curie and an assistant, G. Bmont.                              

Uses -  neutron source, treating cancer, self-luminous paints

 

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

Symbol Ac Name Actinium
Atomic Number 89 Atomic Mass (227) amu
Melting Point 1050C Boiling Point 3200C
Protons/Electrons 89 Neutrons 138
Classification Transition Metal State Solid
Density 10.07 g/cm3 Period/Group 7 / 3
Electronegativity 1.1 Atomic Radius 195 pm
# of Isotopes 2 Color silvery-white
Energy Levels 7 Crystal Structure cubic
Actinium was first discovered in 1899 by Andr-Louis Debierne in pitchblende residues left after the Curies had extracted radium.                 

Uses -   thermoelectric power, source of neutrons

 

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

Symbol Th Name Thorium
Atomic Number 90 Atomic Mass 232.038 amu
Melting Point 1842C Boiling Point 4820C
Protons/Electrons 90 Neutrons 142
Classification Metal State Solid
Density 11.724 g/cm3 Group Actinoid
Electronegativity 1.3 Atomic Radius 179 pm
# of Isotopes 3 Color white
Energy Levels 7 Crystal Structure cubic
Thorium was discovered by Jns Jacob Berzelius in 1828.                                   

Uses -  gas mantles, strong alloys, ultraviolet photoelectric cells, laboratory crucibles, source of nuclear energy

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