(From the Latin fluor, "flux") A corrosive, toxic, greenish-yellow gaseous chemical element, the lightest of the halogens and the most reactive chemical element, forming fluorides with almost all known elements.

Symbol: F
Atomic number: 9
Atomic weight: 18.9984032
Density (at 0°C with 101,325 pascals): 1.696 g/L
Melting point: -219.62°C
Boiling point: -188.1°C
Valence: -1
Ground state electron configuration: [He]2s22p5

Symbol: F
Atomic Number: 9
Boiling Point: 85.0 K
Melting Point: 53.55 K
Density at 300K: 1.696 g/cm3
Covalent radius: 0.72
Atomic radius: 0.57
Atomic volume: 17.10 cm3/mol
First ionization potental: 17.422 V
Specific heat capacity: 0.824 J g-1 K-1
Thermal conductivity: 0.0279
Electrical conductivity: N/A
Heat of fusion: 0.26 kJ/mol
Heat of vaporization: 3.2698 kJ/mol
Electronegativity: 3.98 (Pauling's)

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Flu"or*ine (? ∨ ?; 104), n. [NL. fluorina: cf. G. fluorin, F. fluorine. So called from its occurrence in the mineral fluorite.] Chem.

A non-metallic, gaseous element, strongly acid or negative, or associated with chlorine, bromine, and iodine, in the halogen group of which it is the first member. It always occurs combined, is very active chemically, and possesses such an avidity for most elements, and silicon especially, that it can neither be prepared nor kept in glass vessels. If set free it immediately attacks the containing material, so that it was not isolated until 1886. It is a pungent, corrosive, colorless gas. Symbol F. Atomic weight 19.

Fluorine unites with hydrogen to form hydrofluoric acid, which is the agent employed in etching glass. It occurs naturally, principally combined as calcium fluoride in fluorite, and as a double fluoride of aluminium and sodium in cryolite.


© Webster 1913.
