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Fluorine is a chemical element with symbol F and atomic number 9. It is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions.As the most electronegative element, it is extremely reactive, as it reacts with almost all other elements, except for helium and neon.. Among the elements, fluorine ranks 24th in universal abundance and 13th in terrestrial
the Color of Art Pigment Database the Pigment Yellow page of the database is a complete artists pigment reference, with color Index names, pigment chemical composition, lightfastness, safety and other information on artists pigments and paint.
Heavy metals are generally defined as metals with relatively high densities, atomic weights, or atomic numbers.The criteria used, and whether metalloids are included, vary depending on the author and context. In metallurgy, for example, a heavy metal may be defined on the basis of density, whereas in physics the distinguishing criterion might be atomic number, while a chemist would likely be