Fluorine

Fluorine is a highly toxic pale-yellow diatomic gas with an atomic number of 9. Fluorine is extremely reactive: even noble gases form compounds with it(Noble gases are really not at all as noble as we think of them. They still react with some non metals like fluorine).
==Properties==
Fluorine atoms have nine electrons, one fewer than neon, and electron configuration 1s22s22p5: two electrons in a filled inner shell and seven in an outer shell requiring one more to be filled. The outer electrons are ineffective at nuclear shielding, and experience a high effective nuclear charge of 9 − 2 = 7; this affects the atom's physical properties.
It has a high electron affinity, second only to chlorine, and the highest electronegativity of any element.
==Burning Fluorine and its colour==
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Category:Element