A non-metallic, gaseous element of atomic number 9, strongly acid or negative, and 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, but may be contained in lead vessels. If set free it immediately attacks a containing glass vessel, so that it was not isolated until 1886. It is a pungent, corrosive, colorless gas. Symbol F. Atomic weight 19.00.

A chemical element which takes the form of a toxic, pale yellow gas.

a nonmetallic univalent element belonging to the halogens; usually a yellow irritating toxic flammable gas; a powerful oxidizing agent; recovered from fluorite or cryolite or fluorapatite

A gaseous element that can be poisonous.

Thought to strengthen the mineral composition of tooth enamel, making it resistant to acid attacks Fish, fluoridated water, tea

atomic symbol, F, fluorine is the 9th element in the periodic table ( atomic number 9) with an atomic weight of 18.998. Argon is a group VII element and is highly reactive. Flurine is used in etching gases and chemicals. Fluorine is toxic.

An element of the halogen class of elements which is only found in nature combined with other substances. It is found combined as calcium fluoride in fluorite, and as a double fluoride of aluminum and sodium in cryolite. Fluorine is very active chemically, (the most electronegative and most reactive of all the elements), and possesses such an avidity for most elements, especially silicon, that it can neither be prepared nor kept in glass vessels. This is why even though it was first identified by Scheele in 1771, it was not isolated until 1886 by Moissan. When isolated, fluorine is a pale-yellow, highly corrosive, flammable, poisonous, gas.