What is electronegativity?

Electronegativity is a key concept used to describe bonding and can be defined as the tendency of an atom to attract a bonding pair of electrons. Each element has a unique number of protons, in Hydrogen's case, 1 and in Carbon's case 6.The number of protons is 1 of 2 key factors in determining the electronegativity value of an atom. The greater the number of protons, the greater the electrostatic attraction the atom has towards electrons and thus the greater electronegativity. According to this rule, the value for Eneg increases across the periodic table. The 2nd factor that affects Eneg is the shell number. As you go down a group, even though the proton number increases, electrons are also introduced in an outer shell, physically increasing the distance between the nucleus and the bonding electrons weakening the electrostatic attraction. According to this rule, electronegativity decreases down the group. With group 8 as an exception due to their full shell nature, the most electronegative atom is fluorine and the least electronegative atom (that is stable) is caesium.