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 (E-F-G-H)

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Name: Einsteinium
Symbol: Es
Atomic Number: 99
Atomic Weight: (252)
Group: Actinide
Date Discovered: series 1952
Discovered By: Albert Ghiorso and coworkers

Name: Erbium
Symbol: Er
Atomic Number: 68
Atomic Weight: 167.26
Group: Lanthanide
Date Discovered: series 1843
Discovered By: Carl Mosander

Name: Europium
Symbol: Eu
Atomic Number: 63
Atomic Weight: 151.966
Group: Lanthanide
Date Discovered: series 1901
Discovered By: Eugène Demarçay

Name: Fermium
Symbol: Fm
Atomic Number: 100
Atomic Weight: (257)
Group: Actinide
Date Discovered: series 1955
Discovered By: Albert Ghiorso and coworkers

Name: Fluorine
Symbol: F
Atomic Number: 9
Atomic Weight: 18.9984
Group: Halogens
Date Discovered: 1771
Discovered By: Karl Scheele (isolated by Henri Moissan 1886)

Name: Francium
Symbol: Fr
Atomic Number: 87
Atomic Weight: (223)
Group: Alkali metals
Date Discovered: 1939
Discovered By: Marguérite Perey

Name: Gadolinium
Symbol: Gd
Atomic Weight: 64
Atomic Number: 157.25
Group: Lanthanide
Date Discovered: series 1886
Discovered By: Paul Lecoq de Boisbaudran

Name: Gallium
Symbol: Ga
Atomic Number: 31
Atomic Weight: 69.723
Group: Other
Date Discovered: metals 1875
Discovered By: Paul Lecoq de Boisbaudran

Name: Germanium
Symbol: Ge
Atomic Number: 32
Atomic Weight: 72.61
Group: Other metals
Date Discovered: 1886
Discovered By: Clemens Winkler

Name: Gold
Symbol: Au
Atomic Number: 79
Atomic Weight: 196.9665
Group: Transition metals
Date Discovered: prehistoric
Discovered By: unknown

Name: Hafnium
Symbol: Hf
Atomic Number: 72
Atomic Weight: 178.49
Group: Transition metals
Date Discovered: 1913
Discovered By: Dirk Coster and Georg von Hevesy

Name: Hassium
Symbol: Hs
Atomic Number: 108
Atomic Weight: (263)
Group: Transition metals
Date Discovered: 1984
Discovered By: Peter Armbruster and coworkers

Name: Helium
Symbol: He
Atomic Number: 2
Atomic Weight: 4.0026
Group: Noble gases
Date Discovered: 1868
Discovered By: Pierre Janssen

Name: Holmium
Symbol: Ho
Atomic Number: 67
Atomic Weight: 164.9303
Group: Lanthanide
Date Discovered: series 1879
Discovered By: Per Cleve

Name: Hydrogen
Symbol: H
Atomic Number: 1
Atomic Weight: 1.0079
Group: Nonmetals
Date Discovered: 1766
Discovered By: Henry Cavendish