Their strong acidity is attributed to the electronegativity of the trifluoromethyl group that stabilizes the negative charge.
Thiopyrylium salts are less reactive than the analogous pyrylium salts due to the lower electronegativity of the sulfur atom.
All group 2 elements are electropositive towards carbon and electronegativity decreases down the row.
Elements with low electronegativity, such as most metals, easily donate electrons and oxidize they are reducing agents.
The solute and solvent should have similar electronegativity.
Of the elements within d-block, zirconium has the fourth lowest electronegativity after yttrium, lutetium and hafnium.
Since fluorine is a relatively small atom with a large electronegativity, its covalent radius is difficult to evaluate.
The trifluomethyl group has a significant electronegativity that is often described as being intermediate between the electronegativities of fluorine and chlorine.
