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Fluorine. cubic. Fluorine is a chemical element; it has symbol F and atomic number 9. It is the lightest halogen [note 1] and exists at standard conditions as pale yellow diatomic gas. Fluorine is extremely reactive as it reacts with all other elements except for the light inert gases.
F. ). Only fluorine-19 is stable and naturally occurring in more than trace quantities; therefore, fluorine is a monoisotopic and mononuclidic element. The longest-lived radioisotope is 18. F. ; it has a half-life of 109.734 (8) min. All other fluorine isotopes have half-lives of less than a minute, and most of those less than a second.
A table or chart of nuclides is a two-dimensional graph of isotopes of the elements, in which one axis represents the number of neutrons (symbol N) and the other represents the number of protons (atomic number, symbol Z) in the atomic nucleus. Each point plotted on the graph thus represents a nuclide of a known or hypothetical chemical element.
Francium is a chemical element; it has symbol Fr and atomic number 87. It is extremely radioactive; its most stable isotope, francium-223 (originally called actinium K after the natural decay chain in which it appears), has a half-life of only 22 minutes. [4] It is the second-most electropositive element, behind only caesium, and is the second ...
A number of other elements are named after classical words for various places. Ruthenium is from the Latin name for the region including Belarus, Ukraine, and Russia. [29] Lutetium is named after Lutetia, the Latin name for Paris. Copper's name comes from an Old English word derived from the Latin name for the island of Cyprus. [30]
Lithium is the first alkali metal in the periodic table, [note 1] and the first metal of any kind in the periodic table. [note 2] At standard temperature and pressure, lithium is a soft, silver-white, highly reactive metal. With a density of 0.564 g⋅cm −3, lithium is the lightest metal and the least dense solid element. [6]
e. In the context of the periodic table a nonmetal is a chemical element that mostly lacks distinctive metallic properties. They range from colorless gases like hydrogen to shiny crystals like iodine. Physically, they are usually lighter (less dense) than elements that form metals and are often poor conductors of heat and electricity.
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references. Fluoride (/ ˈflʊəraɪd, ˈflɔːr -/) [3] is an inorganic, monatomic anion of fluorine, with the chemical formula F−. (also written [F]−. ), whose salts are typically white or colorless.