Tantalum (Ta)

Atomic Number: 73

Relative Atomic Mass: 180.94788

Electronegativity: 1.50

Atomic Radius (Picometers): 145

Appearance: Blue-Grey

Occurrence: Natural

Melting Point (Kelvin): 3290

Boiling Point (Kelvin): 5731

Stable Isotopes: 181

Discoverer: Anders Ekeberg in 1802

Properties: Ductile, Hard

First Use: Unknown

Modern Uses: Electronics, Alloys

Picture Courtesy of Alchemist-hp

©2011 Grant Dwyer

Hafnium (Hf)

Atomic Number: 72

Relative Atomic Mass: 178.49

Electronegativity: 1.30

Atomic Radius (Picometers): 155

Appearance: Steel-Grey

Occurrence: Natural

Melting Point (Kelvin): 2506

Boiling Point (Kelvin): 4876

Stable Isotopes: 176, 177, 178, 179, 180

Discoverers: Georges Urbain and Vladimir Vernadsky in 1911

Properties: Ductile

First Use: Unknown

Modern Uses: Control Rods, Microprocessors

Picture Courtesy of Alchemist-hp

©2011 Grant Dwyer

Lutetium (Lu)

Atomic Number: 71

Relative Atomic Mass: 174.96684

Electronegativity: 1.27

Atomic Radius (Picometers): 175

Appearance: Silver-White

Occurrence: Natural

Melting Point (Kelvin): 1925

Boiling Point (Kelvin): 3675

Stable Isotopes: 175

Discoverers: Carl Auer von Welsbach and Georges Urbain in 1906

Properties: Hard

First Use: Unknown

Modern Uses: Nuclear, Alloys

Picture Courtesy of Alchemist-hp

©2011 Grant Dwyer

Ytterbium (Yb)

Atomic Number: 70

Relative Atomic Mass: 173.0545

Electronegativity: 1.10

Atomic Radius (Picometers): 175

Appearance: Silver-White

Occurrence: Natural

Melting Point (Kelvin): 1097

Boiling Point (Kelvin): 1469

Stable Isotopes: 168, 170, 171, 172, 173, 174,176

Discoverer: Jean Charles Galissard de Marignac in 1878

Properties: Malleable, Soft, Ductile

First Use: Unknown

Modern Uses: Gamma Ray Source, Stainless Steel

Picture Courtesy of Jurii

©2011 Grant Dwyer

Thulium (Tm)

Atomic Number: 69

Relative Atomic Mass: 168.93421

Electronegativity: 1.25

Atomic Radius (Picometers): 175

Appearance: Silver-Grey

Occurrence: Natural

Melting Point (Kelvin): 1818

Boiling Point (Kelvin): 2223

Stable Isotopes: 169

Discoverer: Per Teodor Cleve in 1879

Properties: Malleable, Soft, Ductile

First Use: Unknown

Modern Uses: Lasers, X-Ray Sources

Picture Courtesy of Alchemist-hp

©2011 Grant Dwyer

Erbium (Er)

Atomic Number: 68

Relative Atomic Mass: 167.259

Electronegativity: 1.24

Atomic Radius (Picometers): 175

Appearance: Silver-White

Occurrence: Natural

Melting Point (Kelvin): 1802

Boiling Point (Kelvin): 3141

Stable Isotopes: 162, 164, 166, 167, 168, 170

Discoverer: Carl Mosander in 1842

Properties: Malleable, Soft

First Use: Colour Glass (1990's)

Modern Uses: Control Rods, Cryocoolers

Picture Courtesy of Tomihahndorf

©2011 Grant Dwyer