Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative element, it is extremely reactive, as it reacts with all other elements, except for argon, neon, and helium.
Why is the mass number of fluorine 19?
Fluorine (9F) has 18 known isotopes ranging from 13F to 31F (with the exception of 30F) and two isomers (18mF and 26mF). Only fluorine-19 is stable and naturally occurring; therefore, fluorine is a monoisotopic and mononuclidic element, and only artificially produced fluorine isotopes have mass numbers other than 19.
How was fluorine found?
Fluorine was discovered in 1886 by French chemist Henri Moissan (1852-1907). Moissan collected the gas by passing an electric current through one of its compounds, hydrogen fluoride (H 2 F 2 ). ... Fluorine gas is used to make fluorides, compounds that were made part of toothpastes in the 1950s.
