Terbium (Tb): Atomic number: 65, Atomic mass: 158.92534 g.mol -1, Electronegativity: 1.2, Density: 8.3 g.cm-3 at 20°C, Melting point: 1360 °C, Boiling point: 3041 °C, Vanderwaals radius: unknown, Ionic radius: unknown, Isotopes: 9, Electronic shell: [ Xe ] 4f9 6s2, Energy of first ionisation: 563.5 kJ.mol -1, Energy of second ionisation: 1109.6 kJ.mol -1, Standard potential: - 2.39 V, Discovered: Carl Mosander in 1843. Terbium is a soft, malleable, ductile, silver-gray metal member of the lanthanide group of the periodic table. It is reasonably stable in air, but it is slowly oxidised and it reacts with cold water. Applications: Terbium is rare and expensive, so it has few commercial uses. Some minor uses are in lasers, semiconductor devices, and phosphorous in colour television tubes. It is also used in solid-state devices, as stabilizer of fuel cells which operate at high temperature. Terbium in the environment: Terbium is one of the rarer rare-earth elements, although is twice as common in the Earth's crust as silver. It is never found in nature as free element, but is is contained in many minerals. The most important ore are monazite, bastnasite and cerite. The main mining areas are China, USA, India, Sri Lanka, Brazil and Australia and reserves fo terbium are estimated to be around 300.000 tonnes. World production is 10 tonnes a year.

 

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Terbium (Tb): Atomic number: 65, Atomic mass: 158.92534 g.mol -1, Electronegativity: 1.2, Density: 8.3 g.cm-3 at 20°C, Melting point: 1360 °C, Boiling point: 3041 °C, Vanderwaals radius: unknown, Ionic ra . . . View Full Definition

Ytterbium (Yb): Atomic number: 70, Atomic mass: 173.04 g.mol -1, Electronegativity: 1.1, Density: 7 g.cm-3 at 20°C, Melting point: 824 °C, Boiling point: 1466 °C, Vanderwaals radius: unknown, Ionic radius: . . . View Full Definition

Ytterbium: Element 70, atomic weight 173.04, a very rare, malleable metal used in special alloys for X-ray sources.

Tailback (TB): Player position on offense farthest ('deepest') back, except in kicking formations. Also often referred to as the running back, particularly in a one-back offense.