Matter & Energy


Matter is composed of atoms or groups of atoms called molecules. The arrangement of particles in a material depends on the physical state of the substance. In a solid, particles form a compact structure that resists flow. Particles in a liquid have more energy than those in a solid. They can flow past one another, but they remain close. Particles in a gas have the most energy. They move rapidly and are separated from one another by relatively large distances.

Alphabetic list of Chemical Elements (T-U)

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Name: Tantalum
Symbol: Ta
Atomic Number: 73
Atomic Weight: 180.948
Group: Transition metals
Date Discovered: 1802
Discovered By: Anders Ekeberg

Name: Technetium
Symbol: Tc
Atomic Number: 43
Atomic Weight: (98)
Group: Transition metals
Date Discovered: 1937
Discovered By: Carlo Perrier and Emilio Segrè

Name: Tellurium
Symbol: Te
Atomic Number: 52
Atomic Weight: 127.60
Group: Nonmetals
Date Discovered: 1782
Discovered By: Franz Müller

Name: Terbium
Symbol: Tb
Atomic Number: 65
Atomic Weight: 158.9253
Group: Lanthanide
Date Discovered: series 1843
Discovered By: Carl Mosander

Name: Thallium
Symbol: Tl
Atomic Number: 81
Atomic Weight: 204.3833
Group: Other metals
Date Discovered: 1861
Discovered By: William Crookes (isolated by William Crookes and Claude August Lamy, independently of each other, in 1862

Name: Thorium
Symbol: Th
Atomic Number: 90
Atomic Weight: 232.0381
Group: Actinide
Date Discovered: series 1828
Discovered By: Jöns Berzelius

Name: Thulium
Symbol: Tm
Atomic Number: 69
Atomic Weight: 168.9342
Group: Lanthanide
Date Discovered: series 1879
Discovered By: Per Cleve

Name: Tin
Symbol: Sn
Atomic Number: 50
Atomic Weight: 118.711
Group: Other metals
Date Discovered: prehistoric
Discovered By: unknown

Name: Titanium
Symbol: Ti
Atomic Number: 22
Atomic Weight: 47.867
Group: Transition metals
Date Discovered: 1790
Discovered By: William Gregor

Name: Tungsten
Symbol: W
Atomic Number: 74
Atomic Weight: 183.84
Group: Transition metals
Date Discovered: 1783
Discovered By: isolated by Juan José Elhuyar and Fausto Elhuyar

Name: Ununbium
Symbol: Uub
Atomic Number: 112
Atomic Weight: (277)
Group: Transition metals
Date Discovered: 1996
Discovered By: team at the Heavy-Ion Research Laboratory, Darmstadt, Germany

Name: Ununhexium
Symbol: Uuh
Atomic Number: 116
Atomic Weight: (292)
Group: Other metals
Date Discovered: 2000
Discovered By: team at the Joint Institute for Nuclear Research, Dubna, Russia

Name: Ununquadium
Symbol: Uuq
Atomic Number: 114
Atomic Weight: (285)
Group: Other metals
Date Discovered: 1998
Discovered By: team at the Joint Institute for Nuclear Research, Dubna, Russia

Name: Unununium
Symbol: Uuu
Atomic Number: 111
Atomic Weight: (272)
Group: Transition metals
Date Discovered: 1994
Discovered By: team at the Heavy-Ion Research Laboratory, Darmstadt, Germany

Name: Uranium
Symbol: U
Atomic Number: 92
Atomic Weight: 238.0289
Group: Actinide
Date Discovered: series 1789
Discovered By: Martin Klaproth (isolated by Eugène Péligot 1841)