The least electronegative element is francium (Fr), which is the element with the lowest electronegativity value on the periodic table. Francium belongs to Group 1 (alkali metals) and is located at the bottom of the periodic table.
Elements in Group 1 have one valence electron. Valence electrons are the electrons in the outermost energy level (valence shell) of an atom. Since francium is in Group 1, it has a single valence electron in its outermost shell.
It's important to note that francium is a highly reactive and radioactive element with a very short half-life. Due to its rarity and radioactivity, francium is not encountered in significant quantities in nature, and most of its properties are inferred from its position in the periodic table.